OK, so here's a question...

My sister has an Acer Aspire 5000 laptop. It used to work just fine, but 
recently it has developed some disturbing symptoms - basically random 
freezing.

The utterly weird thing is, it behaves perfectly under [several 
different variants of] Linux, but continues to randomly freeze when 
running under Windows. [I have reinstalled Windows several times now. 
Interestingly, it always seems to hang at the same places in the 
installation sequence.]

The symptoms:

- Laptop no longer responds to keyboard or mouse. (Mouse pointer won't 
move, Ctrl+Alt+Del is no-op, the capslock light doesn't function when I 
press the key, etc.)

- On every laptop known to man, holding down the power button will 
forcibly power down the laptop. This does not work while the laptop is 
frozen. (Fortunately the battery typically dies after ~5 minutes or so.)

- The laptop *does* respond to some things though. Unplugging the 
Ethernet cable still pops up that retarded "a cable is unplugged" message.

- The fans seem to spin up while the laptop is hang, suggesting an 
infinite loop in the software somewhere.

- I am reasonably sure the laptop is not overheating. It seems cold to 
the touch, and it repeatedly hangs at *exactly* the point in Windows, 
and has never done this even once under Linux.

- Repeated memory tests reveal no problems of any kind.

- I have reinstalled Windows multiple times, without any Internet 
access, so I'm downright certain it's not a virus or a software 
configuration issue.

To reiterate, when the laptop was new, it had none of these issues. 
(Although it was dissapointingly slow.)

Does anybody have the slightest clue what the *hell* is causing this 
frustrating behaviour?

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Invisible wrote:

Are they any devices/gizmos/etc that don't work on Linux? WLAN?
Bluetooth? Card reader? Anything?

-Aero

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Invisible wrote:
> - On every laptop known to man, holding down the power button will 
> forcibly power down the laptop. This does not work while the laptop is 
> frozen. (Fortunately the battery typically dies after ~5 minutes or so.)

Wow. I was under the impression this was built right into the power 
supplies. Maybe not on a laptop, tho.

I have a friend who was designing motherboards for specialized systems like 
disk array servers. He told me he spent three days trying to figure out why 
the system would power off seven seconds after he plugged it in each time. 
Turns out it took three seconds to initialize the board enough that the 
signal from the power supply could be read, and he'd wired that wire 
backwards, so four seconds later it would turn off again.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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Invisible wrote:
> - On every laptop known to man, holding down the power button will 
> forcibly power down the laptop. 

Here's a thought. See if you can configure the BIOS to turn off APCI stuff? 
The "advanced" power control? Linux tends to handle this differently, and 
perhaps Windows is confused by some problem being caused by this.

No idea why it would crop up after a while, tho.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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On Wed, 07 Jan 2009 16:52:51 +0000, Invisible wrote:

> - Repeated memory tests reveal no problems of any kind.

What are you using to do the memory tests?

Jim

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>> - Repeated memory tests reveal no problems of any kind.
> 
> What are you using to do the memory tests?

memtest86

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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On Wed, 07 Jan 2009 22:16:52 +0000, Orchid XP v8 wrote:

>>> - Repeated memory tests reveal no problems of any kind.
>> 
>> What are you using to do the memory tests?
> 
> memtest86

86, or 86+?  ISTR that 86+ is more thorough, but 86 should be sufficient.

Jim

Post a reply to this message

> The utterly weird thing is, it behaves perfectly under [several different 
> variants of] Linux, but continues to randomly freeze when running under 
> Windows. [I have reinstalled Windows several times now. Interestingly, it 
> always seems to hang at the same places in the installation sequence.]

Sounds to me like it is one particular piece of hardware/driver 
malfunctioning.  Under Linux it either has a different driver or is just not 
used at all (as already mentioned).

I would try booting Windows in safe mode and seeing if that is stable.  If 
so then I would reboot normally and disable all non-critical hardware in 
device manager.  If it is still stable then selectively restart hardware 
until it you find the culprit.  If you are really lucky a driver update 
might fix it...

Post a reply to this message

scott wrote:
>> The utterly weird thing is, it behaves perfectly under [several 
>> different variants of] Linux, but continues to randomly freeze when 
>> running under Windows. [I have reinstalled Windows several times now. 
>> Interestingly, it always seems to hang at the same places in the 
>> installation sequence.]
> 
> Sounds to me like it is one particular piece of hardware/driver 
> malfunctioning.

This is my feeling also. It used to work just fine, and now it doesn't, 
despite multiple reinstalls, which suggests a hardware issue. (But I 
have no idea which bit of hardware.)

I did think perhaps it was the audio - my sister mentioned the sound 
suddenly stopped working a while ago, and sure enough the machine locked 
shortly after I installed the audio drive.

...but then I reinstalled without the audio driver, and it still 
randomly hangs. *sigh*

> I would try booting Windows in safe mode and seeing if that is stable.

Ah, the joy of intermittent faults. Is it *really* gone? Or is it just 
not happening right now? :-/

> If so then I would reboot normally and disable all non-critical hardware 
> in device manager.  If it is still stable then selectively restart 
> hardware until it you find the culprit.  If you are really lucky a 
> driver update might fix it...

Well, currently I have installed Windows plus every update that Windows 
Update will give me. I haven't *seen* it crash since that time, but.....

Post a reply to this message

> Well, currently I have installed Windows plus every update that Windows 
> Update will give me. I haven't *seen* it crash since that time, but.....

Ah, the joy of *extremely* intermittent faults :-)

Have you looked in the Event Viewer (I think it's called that in XP too) to 
see what happened when it crashed?

It seems from your comments that the laptop is still running, just not 
responding to user input.  Is this the internal mouse and keyboard? Try 
plugging in an external USB mouse next time it "freezes".

Post a reply to this message

scott wrote:

> Ah, the joy of *extremely* intermittent faults :-)

Indeed!

> Have you looked in the Event Viewer (I think it's called that in XP too) 
> to see what happened when it crashed?
> 
> It seems from your comments that the laptop is still running, just not 
> responding to user input.  Is this the internal mouse and keyboard? Try 
> plugging in an external USB mouse next time it "freezes".

Yeah, "crashed" would seem an exaggeration. More like "suddenly going 
extremely slowly". (IIRC, the CPU graph in Task Manager stops scrolling, 
for example.)

I'm using the internal glide pad. I didn't have a USB mouse with me. I 
guess I could give that a try...

Post a reply to this message

Darren New wrote:
> Invisible wrote:
>> - On every laptop known to man, holding down the power button will 
>> forcibly power down the laptop. This does not work while the laptop is 
>> frozen. (Fortunately the battery typically dies after ~5 minutes or so.)
> 
> Wow. I was under the impression this was built right into the power 
> supplies. Maybe not on a laptop, tho.

Indeed.

On the other hand, I was *also* under the impression that the cooling 
fan is hardware-controlled. But it turns out to be software-controled. (!!)

I discovered this while trying to install SUSE on my dad's ancient brick 
of a laptop. The install kept failing in bizare and unexplained ways. 
Until I picked up the laptop and almost burnt my hand off!

We rebooted the laptop, and as soon as the BIOS screen showed up, the 
fans started spinning like mad. We waited for them to slow down. (It 
took a while.) Then we resumed the installation attempt. Same problem. 
No matter how hot the laptop got, no fans.

The solution in the end was quite simple. Reboot with the laptop hot. 
The fans spin up to full power. Rather than waiting for them to stop, 
just start installing. The fans remained at full speed until the system 
soft-reset onto the new kernel. After that they appeared to work "normally".

GO. FIGURE.

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> We rebooted the laptop, and as soon as the BIOS screen showed up, the fans 
> started spinning like mad. We waited for them to slow down.

What software was running then while you were waiting?

> The solution in the end was quite simple. Reboot with the laptop hot. The 
> fans spin up to full power. Rather than waiting for them to stop, just 
> start installing. The fans remained at full speed until the system 
> soft-reset onto the new kernel. After that they appeared to work 
> "normally".

I notice when I boot up my Vista box, that every fan runs at full blast 
until some point during Vista boot, whereby first the CPU fan virtually 
turns off, then a few seconds after the desktop appears the GPU fan 
virtually turns off, all I can hear then is just occasional blips of hard 
drive head movement - until I fire up a 3D game, then all hell breaks loose 
again :-)

Post a reply to this message

scott wrote:
>> We rebooted the laptop, and as soon as the BIOS screen showed up, the 
>> fans started spinning like mad. We waited for them to slow down.
> 
> What software was running then while you were waiting?

The BIOS configuration interface.

> I notice when I boot up my Vista box, that every fan runs at full blast 
> until some point during Vista boot, whereby first the CPU fan virtually 
> turns off, then a few seconds after the desktop appears the GPU fan 
> virtually turns off, all I can hear then is just occasional blips of 
> hard drive head movement - until I fire up a 3D game, then all hell 
> breaks loose again :-)

Interesting. All the fans in my PC just run constantly anyway. The four 
harddrives are just about inaudible.

(I can't believe I have four harddrives...)

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>> What software was running then while you were waiting?
>
> The BIOS configuration interface.

So your conclusion is that the BIOS software controls the fan speed, but for 
some reason SUSE manages to disable this fan speed control function of the 
BIOS?  Or that Windows has its own fan speed control software?

>> I notice when I boot up my Vista box, that every fan runs at full blast 
>> until some point during Vista boot, whereby first the CPU fan virtually 
>> turns off, then a few seconds after the desktop appears the GPU fan 
>> virtually turns off, all I can hear then is just occasional blips of hard 
>> drive head movement - until I fire up a 3D game, then all hell breaks 
>> loose again :-)
>
> Interesting. All the fans in my PC just run constantly anyway.

There should be an option in the BIOS to control the CPU fan speed based on 
temperature, it can be disguised under a number of weird names (I think mine 
is "AI Fan Control" or something stupid like that).

As for the GPU fan (which is far louder on my machine than the CPU fan), it 
seems this is built into the OS/driver.  Actually I don't remember XP ever 
reducing the speed, so maybe it's something new for Vista?

> The four harddrives are just about inaudible.

So are mine when the GPU fan is on!

Post a reply to this message

scott wrote:
>>> What software was running then while you were waiting?
>>
>> The BIOS configuration interface.
> 
> So your conclusion is that the BIOS software controls the fan speed, but 
> for some reason SUSE manages to disable this fan speed control function 
> of the BIOS?  Or that Windows has its own fan speed control software?

My conclusion is that Windows (and SUSE when it's finished installing) 
controls the fan speed, but the SUSE installation program doesn't.

>> Interesting. All the fans in my PC just run constantly anyway.
> 
> There should be an option in the BIOS to control the CPU fan speed based 
> on temperature, it can be disguised under a number of weird names (I 
> think mine is "AI Fan Control" or something stupid like that).

Possibly I need to install AMD's Cool'n'Quiet driver or something, IDK.

(The idea of a "processor driver" is highly amusing to me. Of course, 
it's not actually a driver for the *processor* at all. It's a driver for 
some of the processor's special features, like frequency scaling, fan 
speeds, power management, etc.)

> As for the GPU fan (which is far louder on my machine than the CPU fan), 
> it seems this is built into the OS/driver.  Actually I don't remember XP 
> ever reducing the speed, so maybe it's something new for Vista?

I don't know. But if I ever get the cash for a more powerful 3D card, 
presumably it'll be far louder. ;-)

>> The four harddrives are just about inaudible.
> 
> So are mine when the GPU fan is on!

I'm just glad there's an indicator light on the front! Unfortunately, 
only one, not one for each HD.

It's a pitty nobody has ever had the forethought to put a network 
activity indicator on the front of the case. (Dell came close - their 
OptiPlex cases have a link light.)

Post a reply to this message

Invisible wrote:
> OK, so here's a question...
> 
> My sister has an Acer Aspire 5000 laptop. It used to work just fine, but 
> recently it has developed some disturbing symptoms - basically random 
> freezing.
> 

I have an aspire 5100 that did the same thing for about the 1st year 
that I had it.  I tried all sorts of things, but no change.  It would 
freeze with a weird pattern on the screen and nothing would bring it 
back.  I forget if the power button worked or if I had to pull the 
battery to get it to turn off.  It was very annoying as whatever I would 
be working on would be lost.

I tried reinstalling windows, upgrading drivers, the works, no luck.

I gave up on trying to fix it and just saved frequently.

Now it works flawlessly - I don't know what fixed it, and I don't know 
what was wrong, but it doesn't lock up anymore at all.  I can't remember 
the last time it froze.


My guess was the wireless drivers, but I have nothing to substantiate 
it.  Try using it with the wireless turned off and see if that changes 
anything.





Tom

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Invisible wrote:
> On the other hand, I was *also* under the impression that the cooling 
> fan is hardware-controlled. But it turns out to be software-controled. (!!)

Well, keeping it at the selected speed is hardware. Selecting what speed to 
keep it at is software. But I know what you mean.

> No matter how hot the laptop got, no fans.

Most BIOSen I've seen have a flag that says whether you want the OS or the 
BIOS to control the speed.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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scott wrote:
> I notice when I boot up my Vista box, that every fan runs at full blast 
> until some point during Vista boot,

Most times the BIOS (or whatever firmware is on the gfx card) will set the 
fans to full speed on reset, just for safety.

> all I can hear then is just occasional blips of 
> hard drive head movement 

What confuses me is I can turn on a hard drive that has no activity on it, 
and it'll sit there making little chuckling noises, seeking around and such. 
Like, even a USB drive not plugged into a USB cable will click and seek and 
such.  I'm assuming the firmware is testing the drive or something, looking 
for sectors to spare out, but it' kind of weird.

At least if you let Vista sit for a couple hours, all the background crap 
finishes up and the drive stops working.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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Darren New wrote:
> Invisible wrote:
>> On the other hand, I was *also* under the impression that the cooling 
>> fan is hardware-controlled. But it turns out to be software-controled. 
>> (!!)
> 
> Well, keeping it at the selected speed is hardware. Selecting what speed 
> to keep it at is software. But I know what you mean.
> 
>> No matter how hot the laptop got, no fans.
> 
> Most BIOSen I've seen have a flag that says whether you want the OS or 
> the BIOS to control the speed.

I guess I just *assumed* that a safety-critical feature like "don't burn 
down my house" would be hard-wired into the device. You know, like how 
your boiler turns off when the house is warm, without needing any 
software. Apparently not...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Tom Austin wrote:

> I have an aspire 5100 that did the same thing for about the 1st year 
> that I had it.

Oh... good. o_O

Nice to know it's well-designed then. :-/

Seriously, I bought my sister a new laptop because hers was lame. This 
new one is really failing to impress me.

> Now it works flawlessly - I don't know what fixed it, and I don't know 
> what was wrong, but it doesn't lock up anymore at all.  I can't remember 
> the last time it froze.
> 
> 
> My guess was the wireless drivers, but I have nothing to substantiate 
> it.  Try using it with the wireless turned off and see if that changes 
> anything.

Well, initially I didn't even *install* the wireless drivers. (I 
couldn't, because I didn't have them to hand.) Made no difference. Ditto 
for sound and video.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Orchid XP v8 wrote:
> I guess I just *assumed* that a safety-critical feature like "don't burn 
> down my house" would be hard-wired into the device. 

I don't think CPU temperature is safety critical. The CPU basically burns 
out before the heat gets high enough to set anything outside the case on fire.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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>> I guess I just *assumed* that a safety-critical feature like "don't 
>> burn down my house" would be hard-wired into the device. 
> 
> I don't think CPU temperature is safety critical. The CPU basically 
> burns out before the heat gets high enough to set anything outside the 
> case on fire.

Well, perhaps. But CPU temperature is *utterly* critical to being able 
to continue using your laptop. If it gets hot enough, the CPU will burn 
out, and then your laptop is a very expensive paper weight. (!)

I'd be... kind of "upset" if that happened to me. o_O

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Orchid XP v8 wrote:
>>> I guess I just *assumed* that a safety-critical feature like "don't 
>>> burn down my house" would be hard-wired into the device. 
>>
>> I don't think CPU temperature is safety critical. The CPU basically 
>> burns out before the heat gets high enough to set anything outside the 
>> case on fire.
> 
> Well, perhaps. But CPU temperature is *utterly* critical to being able 
> to continue using your laptop. If it gets hot enough, the CPU will burn 
> out, and then your laptop is a very expensive paper weight. (!)

Yep. But that's not safety critical. :-) Indeed, that's exactly why it 
*isn't* safety critical.  Unlike say batteries blowing up, which *are* 
safety critical and which therefore have hardware in the charger to keep 
from blowing them up.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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Orchid XP v8 wrote:
> 
> Well, perhaps. But CPU temperature is *utterly* critical to being able
> to continue using your laptop. If it gets hot enough, the CPU will burn
> out, and then your laptop is a very expensive paper weight. (!)

Then they can sell you a new one (naturally you'll buy the same brand as
the one that melted, won't you?).

-Aero

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> What confuses me is I can turn on a hard drive that has no activity on it, 
> and it'll sit there making little chuckling noises, seeking around and 
> such. Like, even a USB drive not plugged into a USB cable will click and 
> seek and such.  I'm assuming the firmware is testing the drive or 
> something, looking for sectors to spare out, but it' kind of weird.

Probably some sort of continuous calibration system to account for 
temperature changes etc, I guess the head movement mechanisms need to be 
controlled pretty accurately!

Post a reply to this message

> Well, perhaps. But CPU temperature is *utterly* critical to being able to 
> continue using your laptop. If it gets hot enough, the CPU will burn out, 
> and then your laptop is a very expensive paper weight. (!)

Can this actually happen though, or does the CPU just shut down before it 
knows it is going to melt?

When I built my sister's PC the heat sink clip had snapped without me 
knowing, so the heat sink was hanging off one side.  Every time I tried to 
install Windows it just turned off after about 20 seconds.  It wasn't until 
I took the case off that I realised the problem.

Post a reply to this message

scott wrote:
>> What confuses me is I can turn on a hard drive that has no activity on 
>> it, and it'll sit there making little chuckling noises, seeking around 
>> and such. Like, even a USB drive not plugged into a USB cable will 
>> click and seek and such.  I'm assuming the firmware is testing the 
>> drive or something, looking for sectors to spare out, but it' kind of 
>> weird.
> 
> Probably some sort of continuous calibration system to account for 
> temperature changes etc, I guess the head movement mechanisms need to be 
> controlled pretty accurately!

Yeah, I always thought the sounds a HD makes when turned on was just the 
drive mechanism trying to find track 0 or something like that.

Post a reply to this message

Eero Ahonen wrote:
> Orchid XP v8 wrote:
>> Well, perhaps. But CPU temperature is *utterly* critical to being able
>> to continue using your laptop. If it gets hot enough, the CPU will burn
>> out, and then your laptop is a very expensive paper weight. (!)
> 
> Then they can sell you a new one (naturally you'll buy the same brand as
> the one that melted, won't you?).

Yes, I *will* buy the same CPU brand as the melted one. You know why? 
The rival brand uses a different socket. :-P

OTOH, it would probably be both *cheaper* and more beneficial to just 
buy an entire new laptop! ;-)

Post a reply to this message

scott wrote:
>> Well, perhaps. But CPU temperature is *utterly* critical to being able 
>> to continue using your laptop. If it gets hot enough, the CPU will 
>> burn out, and then your laptop is a very expensive paper weight. (!)
> 
> Can this actually happen though, or does the CPU just shut down before 
> it knows it is going to melt?

I am unsure. One would hope that powering down the system if a 
hard-limit temperature is reached *is* in hardware rather than software. 
OTOH, here we have a laptop which got sufficiently hot for the CPU to 
malfunction fairly seriously, yet still the power remains on.

Post a reply to this message

> I am unsure. One would hope that powering down the system if a hard-limit 
> temperature is reached *is* in hardware rather than software. OTOH, here 
> we have a laptop which got sufficiently hot for the CPU to malfunction 
> fairly seriously, yet still the power remains on.

http://www.tomshardware.com/reviews/hot-spot,365.html

It's quite old, but the basic outcome seems to be that the Intel CPUs are 
impossible to damage by overheating.  With the AMD chip it relies on the 
motherboard, but their demo shows that a motherboard temperature sensor 
cannot react quickly enough to avoid frying the CPU when the HS comes off.

Post a reply to this message

scott wrote:

> http://www.tomshardware.com/reviews/hot-spot,365.html
> 
> It's quite old, but the basic outcome seems to be that the Intel CPUs 
> are impossible to damage by overheating.  With the AMD chip it relies on 
> the motherboard, but their demo shows that a motherboard temperature 
> sensor cannot react quickly enough to avoid frying the CPU when the HS 
> comes off.

Oh wow... 370°C after 1 second? That's pretty special!

Looking at this, it seems that in "the old days" some CPUs didn't have 
any temperature sensors at all. I would imagine given the *huge* amounts 
of heat that newer CPUs generate, this must have changed by now.

I still don't know whether the fan speed is hardware or software 
controlled, but I would think by now the system will at least turn 
itself off in a thermal emergency without software intervention.

As an aside... How much heat does the human brain generate? (By every 
estimate I've seen, it has vastly superior theoretical computational 
power compared to any supercomputer yet built by man.) How come human 
brains don't ignite and burn during normal operation? I don't see any 
really large heat sinks on a human...

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On Fri, 09 Jan 2009 10:04:54 +0000, Invisible <voi### [at] devnull> wrote:

> How come human 
>brains don't ignite and burn during normal operation? I don't see any 
>really large heat sinks on a human...

It is fluid cooled and what about those heatsinks on the side of your head? 
-- 

Regards
     Stephen

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>> How come human 
>> brains don't ignite and burn during normal operation? I don't see any 
>> really large heat sinks on a human...
> 
> It is fluid cooled and what about those heatsinks on the side of your head? 

Water cooled? Elite!

But I mean, *damn*, you'd have to have a high-volume fluid pumping 
system, and a very large surface area to dissapate the heat over.



...oh, wait...

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> As an aside... How much heat does the human brain generate?

You can do a quick estimation by seeing how much heat is radiated, the skin 
temperature is approximately 32 degrees, room temperature is 20 degrees, and 
the surface area of your head is, umm about 0.08m^2.  Using the 
Stefan-Boltzmann law I make that about 6W of radiated heat.  Given that the 
human body generates about 100W, I think the 6W figure is too low, as some 
of the heat from the brain will be taken into the body by the blood stream 
(liquid cooling!).  I guess around 20W would be a more sensible figure.


> (By every estimate I've seen, it has vastly superior theoretical 
> computational power compared to any supercomputer yet built by man.)

If my computer were as slow as me doing sums it would probably run on solar 
power in the dark!  And if I tried to do 3 billion sums in one second my 
head would surely explode.

Post a reply to this message

scott wrote:
>> As an aside... How much heat does the human brain generate?
> 
> Given 
> that the human body generates about 100W, I think the 6W figure is too 
> low, as some of the heat from the brain will be taken into the body by 
> the blood stream (liquid cooling!).  I guess around 20W would be a more 
> sensible figure.

http://vadim.oversigma.com/MAS862/Project.html

Suggests that the entire body consumes about 100W, and the brain itself 
uses 20 - 40 W. (So... a pretty significant fraction, considering that 
the human body is *not* a data processing device, primarily.) That's how 
much energy it *uses*, I wonder how much of that ends up as heat?

>> (By every estimate I've seen, it has vastly superior theoretical 
>> computational power compared to any supercomputer yet built by man.)
> 
> If my computer were as slow as me doing sums it would probably run on 
> solar power in the dark!  And if I tried to do 3 billion sums in one 
> second my head would surely explode.

Well, you say that, but how many "sums" does it take to compare a 
snippet of sound to many millions of other recorded examples like it and 
determine that, yes, this is The Beetles singing "All you need is love"?

The human brain doesn't work the same way a computer does. This isn't 
exactly news. Indeed, this is why computers are useful in the first 
place! But based on the number of switching elements in a computer vs 
those in the brain, AFAIK the brain comes out rather favourably.

(The same website above gives the number of transisters in a Pentium IV 
as K * 10^7, while the number of neurons in a brain is K * 10^11. Kind 
of a big difference...)

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Invisible wrote:

> http://vadim.oversigma.com/MAS862/Project.html

"The power consumption of the Pentium 4 may exceed that of the human 
brain. That explains why Pentium cooling systems are getting close in 
size to the human head."

I LOLd! :-D

Post a reply to this message

> Suggests that the entire body consumes about 100W, and the brain itself 
> uses 20 - 40 W. (So... a pretty significant fraction, considering that the 
> human body is *not* a data processing device, primarily.) That's how much 
> energy it *uses*, I wonder how much of that ends up as heat?

Well there aren't too many options for "used energy" to be converted to. 
Maybe some is used to increase the kinetic energy of some blood, but I would 
say that almost all is converted to heat.

> The human brain doesn't work the same way a computer does. This isn't 
> exactly news. Indeed, this is why computers are useful in the first place! 
> But based on the number of switching elements in a computer vs those in 
> the brain, AFAIK the brain comes out rather favourably.

I guess the brain also makes even Windows ME look good for uptime records 
:-)

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scott wrote:
>> Suggests that the entire body consumes about 100W, and the brain 
>> itself uses 20 - 40 W. (So... a pretty significant fraction, 
>> considering that the human body is *not* a data processing device, 
>> primarily.) That's how much energy it *uses*, I wonder how much of 
>> that ends up as heat?
> 
> Well there aren't too many options for "used energy" to be converted to. 
> Maybe some is used to increase the kinetic energy of some blood, but I 
> would say that almost all is converted to heat.

Well, I guess the brain does use *some* of that energy for chemical 
transformations. (It turns raw ingredients into hormones and releases 
them, for example.) But yeah, *most* of it is porbably heat...

FWIW, how much heat does an Intel Core 2 Quad generate?

> I guess the brain also makes even Windows ME look good for uptime 
> records :-)

HAHAHAH! PWN3D! :-D

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> FWIW, how much heat does an Intel Core 2 Quad generate?

About 120W under full load.

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scott wrote:
>> FWIW, how much heat does an Intel Core 2 Quad generate?
> 
> About 120W under full load.

...so, more than an entire human being?

Perhaps *this* is why the human brain is in little danger of burning to 
a crisp? ;-)

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On Fri, 09 Jan 2009 10:26:48 +0000, Invisible <voi### [at] devnull> wrote:

>>> How come human 
>>> brains don't ignite and burn during normal operation? I don't see any 
>>> really large heat sinks on a human...
>> 
>> It is fluid cooled and what about those heatsinks on the side of your head? 
>
>Water cooled? Elite!
>
>But I mean, *damn*, you'd have to have a high-volume fluid pumping 
>system, and a very large surface area to dissapate the heat over.
>
>
>
>...oh, wait...

Yes, the cardiovascular system is an effective heat exchanger working with the
lungs and skin. :)
-- 

Regards
     Stephen

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>> About 120W under full load.
>
> ...so, more than an entire human being?
>
> Perhaps *this* is why the human brain is in little danger of burning to a 
> crisp? ;-)

Maybe not burning to a crisp, but if you raise the temperature of your 
innards by just a few degrees things begin to screw up very rapidly.  You 
have quite a sophisticated temperature control system to keep you at around 
37 degrees inside...

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Stephen wrote:

>> ...oh, wait...
> 
> Yes, the cardiovascular system is an effective heat exchanger working with the
> lungs and skin. :)

More impressive is the scientific *fact* this this system is somehow 
able to keep the contents of the human body at a temperature drastically 
*lower* than the surrounding ambient, even though the human body itself 
generates heat, in utter defience of the 2nd law of thermodynamics.

I'd never believe it if I hadn't seen it with my own eyes...

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scott wrote:

> Maybe not burning to a crisp, but if you raise the temperature of your 
> innards by just a few degrees things begin to screw up very rapidly.  
> You have quite a sophisticated temperature control system to keep you at 
> around 37 degrees inside...

Or, to put it the correct way round, your life processes are designed to 
work at one specific temperature *because* you have an elaborate system 
designed to keep things at exactly that temperature. ;-)

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> More impressive is the scientific *fact* this this system is somehow 
> able to keep the contents of the human body at a temperature drastically 
> *lower* than the surrounding ambient, even though the human body itself 
> generates heat, in utter defience of the 2nd law of thermodynamics.

http://en.wikipedia.org/wiki/Evaporation

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On Fri, 09 Jan 2009 11:48:15 +0000, Invisible <voi### [at] devnull> wrote:

>Stephen wrote:
>
>>> ...oh, wait...
>> 
>> Yes, the cardiovascular system is an effective heat exchanger working with the
>> lungs and skin. :)
>
>More impressive is the scientific *fact* this this system is somehow 
>able to keep the contents of the human body at a temperature drastically 
>*lower* than the surrounding ambient, even though the human body itself 
>generates heat, in utter defience of the 2nd law of thermodynamics.
>
>I'd never believe it if I hadn't seen it with my own eyes...

Sorry, but the ambient temperature is generally lower than body temperature.
When it is higher we use evaporation, as Scott says. 
Although it is amazing the temperatures that we can tolerate. Once I was working
above a gas turbine and the air temperature was 99 °C.
-- 

Regards
     Stephen

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>> More impressive is the scientific *fact* this this system is somehow 
>> able to keep the contents of the human body at a temperature drastically 
>> *lower* than the surrounding ambient, even though the human body itself 
>> generates heat, in utter defience of the 2nd law of thermodynamics.
>>
>> I'd never believe it if I hadn't seen it with my own eyes...
> 
> Sorry, but the ambient temperature is generally lower than body temperature.

Yes, _usually_ it is, and this is quite unsurprising.

> When it is higher we use evaporation, as Scott says. 

I watched some people put a guy in a room at 40°C, and yet somehow he 
didn't die. Indeed, although he came out looking half dead, a 
radiothermometer confirms that his *internal* temperature barely moved. 
It went up something like 0.1°C, which is nothing.

> Although it is amazing the temperatures that we can tolerate. Once I was working
> above a gas turbine and the air temperature was 99 °C.

Interesting. I'm told 80°C is the threshold of pain (and also burns 
damage), so I would have expected 99°C to be a fatality without some 
*serious* protective clothing...

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On Fri, 09 Jan 2009 12:55:19 +0000, Invisible <voi### [at] devnull> wrote:

>
>I watched some people put a guy in a room at 40°C, and yet somehow he 
>didn't die. Indeed, although he came out looking half dead, a 
>radiothermometer confirms that his *internal* temperature barely moved. 
>It went up something like 0.1°C, which is nothing.
>

Again several years ago, when I was working offshore, I worked for two days on a
separation train where the ambient temperature was IIRC about 50deg C. There was
a team of us taking turns monitoring the instrumentation as the HVAC system had
failed. We would spend about 30 mins in the heat and 30 mins cooling down then
back into the heat. All of us were able to keep it up foe 12 hours a day. I
can't remember how much water we drank but we were given salt tablets as well.
Remember "Production Rules". :)

>> Although it is amazing the temperatures that we can tolerate. Once I was working
>> above a gas turbine and the air temperature was 99 °C.
>
>Interesting. I'm told 80°C is the threshold of pain (and also burns 
>damage), so I would have expected 99°C to be a fatality without some 
>*serious* protective clothing...

No serious PPE (Personal Protective Equipment). Safety boots, jeans, tee shirt,
overalls, leather/cotton gloves and hard hat. I tried removing my tee shirt but
the metal on the overalls was too hot to touch. I know what the temperature was
because I took a mercury thermometer up to check as I wanted to know what the
temperature was and a bi-metallic strip thermometer was reading over 100C.
-- 

Regards
     Stephen

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Stephen wrote:

> No serious PPE (Personal Protective Equipment). Safety boots, jeans, tee shirt,
> overalls, leather/cotton gloves and hard hat. I tried removing my tee shirt but
> the metal on the overalls was too hot to touch. I know what the temperature was
> because I took a mercury thermometer up to check as I wanted to know what the
> temperature was and a bi-metallic strip thermometer was reading over 100C.

Damn. Well considering that permanent tissue damage occurs at 80°C, I 
can only assume that your drenched clothing somehow kept you a few 
degrees cooler than that or something. (Surely water must evapourate 
stupidly fast at almost boiling point!)

Reminds me of the time I was trapped by a fire. I didn't realise that 
skin could actually excrete water that fast. I'm not kidding, I had 
water *pouring* off me like water flows out of a tap. I have no idea how 
much water there is in the human body, but I'd suggest fatal dehydration 
couldn't take very long at that speed. (I had one *bad* headache 
afterwards!)

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