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Message 10745 - Posted: 21 Jun 2009 | 8:51:37 UTC

The influence of the CPU

If you look at the top computers that are crunching GPUGRD the CPU times are low between 1000 to 2000 for 4000 to 5000 credits.
Most are i7 CPUs and are using a couple of 295s

So has anyone done some research into what CPU setup is doing the best?

I notice AMD CPUs seem to use a lot of CPU time to to do a WU.

While the GPU cards are a known factor "we found GT200 to be 41% faster per GFLOP than G9x, so the BOINC benchmark underestimates this influence (it could not possibly reflect it correctly unless it used the actual GPU-Grid code)"
there is some huge differences in the amount of CPU time to do WUs

Assuming the WU is done within 24hrs I have had diffences of 1000 cpu time for 4500 credits to 6000 for 4500 credits.

So, can anyone explain the diffences between computers doing the same type of file?
Ross

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ExtraTerrestrial Apes
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Message 10749 - Posted: 21 Jun 2009 | 10:46:27 UTC - in response to Message 10745.

Two facts first:
- the amount of neccessary cpu time depends on the WU
- on the 1st page of the top hosts there are only 2 AMD systems and both use linux, where cpu usage is a lot higher -> this is not cpu-related

Doing a quick check I find the following:
4,971.51 credit WU (high cpu usage)
- i7 2850s
- C2Q 2500s
- Ph II 3025s

5,535.51 credit WU (low cpu usage)
- i7 550s
- C2Q 430s
- Ph II 680s

Note that the i7 and the P2 run stock GTX 295 (1.25 GHz), whereas the C2Q runs significantly OCed (1.51 GHz), so its CPU is working for a shorter amount of time. And most importantly: we can't know the clock speeds. At stock these CPUs are approximately comparable, but any of them could be clocked at least 30% higher, which would reduce the cpu seconds needed for the same task.

MrS
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Ross*
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Message 10750 - Posted: 21 Jun 2009 | 11:01:04 UTC - in response to Message 10749.

Point taken

So do i7 machines e.g 920s only show up as 2.67 not what they are OC too?
next week my i7 920 arrives OC to 3.4 but will have a 4870x2 so I mostly will be doing Milkyway@home or folding@home with that.

It will be interesting to see who runs the first ASUS Mars 295 and the results they get.

Thanks
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Message 10753 - Posted: 21 Jun 2009 | 15:19:36 UTC - in response to Message 10750.

BOINC doesn't show the real clock speed. One could try to guess it from benchmark values, but this is tough as it differs from version to version.

The Mars? Pretty uninteresting in my point of view. For gaming you could just as well get 2 285 for a fraction of the price and for GPU-Grid you could get about 3 295 for that money, which should be at least 2.5 times more productive.

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Message boards : Number crunching : The influence of the CPU