Am 24.08.2018 um 15:51 schrieb William F Pokorny:

> Interesting - especially it not slowing over time. Supposing:

Why should they?

Modern CPU cooling systems dissipate heat very quickly. If POV-Ray were
to max out the cooling system's capacity, it would show within a couple
of seconds.

> Mike posted a wikipedia link for the i5 generations and something which
> caught my eye there is the turbo boost is being applied to your
> processor relatively evenly across all cores. 10/10/11/11/11/12
> multipliers of 100mhz where on older processors it was more unevenly
> boosted and by less. Expect this playing a part in your good performance
> too.
> 
> I wonder if having the hyperthreading circuitry off in each core - my
> understanding is it is there, but disabled - allows each core to run
> cooler? There would be less demand for on die core specific storage too
> I guess with just one thread.

Probably. There's more chip area than if the HT circuitry were
completely absent, so there's more area to dissipate the heat. Also, the
components that would normally be shared between HT units won't be maxed
out and thus create less heat. So given the same cooling system, with HT
off the CPU will indeed inevitably run cooler. But the CPU may be
specified at a lower TDP, in which case a weaker cooling system may be
employed and thus resulting in the same CPU temperature.

I'm not sure whether Intel does indeed produce cores with HT circuitry
existing yet disabled, but producing non-HT CPUs in this manner does
make sense: You can just produce HT CPUs, and if during die testing you
find that a CPU has defective "semi-cores" you can just blow a fuse to
disable HT and sell it as a lower-tier CPU.

Intel has employed this strategy at least as early as the 80486 days,
when they sold dies with functional FPUs as 80486-DX, and those with
faulty FPUs got a fuse blown and sold as FPU-less 80486-SX. And the
external 80487 FPUs you could buy to upgrade such systems were actually
fully-fledged 80486-DX dies that would just take over the entire system,
disabling the 80486-SX installed in the mainboard's CPU socket.


> My memory not quite right on things with respect to the current
> generation of i5s, but the more cores no threads direction at similar
> price is good news for POV-Ray.

Please don't call it "no threads". Threads are a software thing, a means
of utilizing multiple cores by a single application without too much
overhead. The hardware thing is "hyperthreading", a means of multiple
execution units sharing certain functional blocks in the CPU to utilize
them more efficiently.

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