Le 25/07/2010 04:50, somebody nous fit lire :
> "Le_Forgeron" <jgr### [at] freefr> wrote in message

>> A 650 W power supply might have been more than enough (but running a
>> Seasonic X-750 anyway), GTX470 recommands a 550W PSU, power-peak never
>> occurs at the same time as hard drive spin up)
> 
> Yes. I was running with the assumption that bigger is better (and runs
> quieter, cooler and longer) at 50%-60% capacity than a smaller one utilizing
> 70-80%. However, I'm not averse to saving a few bucks if this assumption is
> not warranted.

The assumption is not that false, but there is more between
certification label than between full capacity.

Cooler, for the PSU, is a function of the efficiency.
For a load of 500W, a PSU 80+(basic label) would be at 50%, from 80+
program, it means that 80%=500W, so 100% is 625W, 125W of heat.

80+ label is flat whatever the load ratio, so using a 800W or 1200W
would get the same 80%, and for a load L, the same heat (125W here)

a 750W PSU 80+gold (have to dimension it because the standard provide a
curve for that label) would be between 87 and 92%, for the same load of
500W, at worst 575W and at best 544W : 45W to 75W of heat instead of 125W.
a 1000W PSU 80+gold would be at 90 or 92% (according to power supply
being 115 or 230V): in the 50W range of waste for 500W load.

The ratio is between 2 and 3, for the same service at the end.

It's not about saving a few buck on buy, it also about not spending an
extra on the monthly bill of electricity and less heat out of the case.
On the long term, the better 80+ label is somehow better.

For the quieter, check the review of your candidate PSU(s).
My PSU is a bit "abnormal" (from observed usual behaviour): at low load
(20% according to the manufacturer), the fan would stop. You cannot be
more quieter. (the fan is temperature controled by the PSU in fact)

> 
>> Be aware: on dual monitor, GTX470 reach 72°C, whereas in single monitor,
>> it is far cooler (less than 50°C)
> 
> Interesting (and disappointing). Is this true even if the second one is not
> running anything needing 3D acceleration? If so, would you recommend messing
> with an additional card (different, cheaper and quieter)? I've quickly
> checked and Windows 7 seems to accomodate this...

The factory limit for GTX serie is 105°C, as reported in their reviews.

At least for the value I provided (72°C), that's with a 1920x1200
+1600x1200 settings (both DVI), currently used with gnome desktop with
compiz (a webbrower, a newsreader, a desktop and some fancy applets on
bars). Compiz might use OpenGL (I do not really know).
All cpu core at lowest rate (1.6GHz). (so, not really doing anything)
There are options in the nvidia drivers which might influence, I did not
play with the options (Performance mode is Maximum Performance, at 72°C
the fan speed is reported as 42%).
My driver version is 195.36.24, a bit conservative, latest are 256.35 on
nvidia site now.

I wanted a nvidia because I get a very bad experience with ati & DRI on
linux in the past (more than a PITA, never get it working correctly) and
dual screen was also painfull to set (in contrast to the setting with a
nvidia card) also in linux. YMMV.
I wanted a single ship card because dual screen is better supported in
linux in that configuration (dual chips or cards seems troublesomes in
that domains: I had enough troubles in the past to just want a simple
solution: plug & play, no hack, no editing... I would say "Thanks ATI
for that learning".).

I wanted a powerfull card as I play some mmorpg which are a bit "heavy"
in the graphic zone (previous CPU was kind of ok, previous card was the
limiting factor).
A GTX480 was not considered worth the extra money.

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