[Beowulf] /. Cooler room or cooler servers?
hahn at physics.mcmaster.ca
Thu Apr 7 16:27:30 PDT 2005
> > > No mention of PowerPC which runs far cooler (1/2?) than Intel/AMD:
> >except that it doesn't.
> > > http://www.terrasoftsolutions.com/products/apple/power-useage.pdf
> >lovely graph. alas, the numbers are pure fantasy. yes, I actually
> >did measure a dual xserve g5 (not heavily configured) and it was 200-210W,
> >quite comparable to dual-opterons and even dual-xeons.
is there some reason to believe I'd deliberately arrange an unfair
comparison? in any case, these factors don't matter that much.
the point is that the true dissipation of 200-210W is drastically differt
from the macophile reputation of these machines. at the time, what
I had to compare with were duals like HP Dl145 (8G, 1.8's). iirc
those are around 220W; the same machine with a 2.2 peaks at 240.
obviously, the new opteron rev would be noticably cooler.
> However, if we do a straight watts/GHz, Xeon is 34.375, G4 is 33.8 ... not
> too much difference.
I'm not sure where those numbers come from - I hope you're not just using
Intel's TDP numbers (which are not max-dissipation numbers.)
W/GHz is amusing; here are some other numbers:
w ghz w/ghz
amd 143 2.2 65
intel sc 214 3.0 71.3
intel dc 242 2*2.8 43.2
of course, the AMD looks even better if you scale by performance rather than clock.
> One also needs to look at important ancillary issues like power consumption
> of the cache, bus drivers, etc. And, of course, instruction stream makes a
> big difference.
kind of obvious, don't you think? when I said peak, I meant peak,
and I'm quoting power dissipation measured at the wall plug (kill-a-watt).
for these systems, running two compute-intensive programs maxes out;
messing with memory or disks only adds a few watts (percent).
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