MultiGPU help

[SatTech]

Ok, I bought myself a few early x-mas stocking stuffers: 2 x 9800GX2s, MSI K9A2 MB, and a 750w Corsair PS with the intent of building a nice 8 core folding box. I know I'll need more power when I add the 3rd (possibly) and 4th (for sure) cards, but that most likely won't be for several months. Anybody have any idea how many processor cores are needed to feed 8 gpu clients? I've got a spare 5000+ Black Edition laying around. If not, I could probably pull the 9850 Phenom from my media server (or upgrade to the new 45nm parts when they become available). I'm guessing the dual core is enough to feed 4 clients for now.

Thanks for the help

 

[styx0r]

You do not need more than 2 cores. 4gpu/core. If you look around, you will notice that GPU clients seem to use more CPU power in XP v.s. Vista - It has been suggested that XP is incorrectly reporting the CPU usage (as 100%), when in reality, actual usage is far lower.

My own experience suggests this is true - I am powering (4) 8800GTs with a slow dual core AMD, running XP, and (3) 8800GTs with a dual core 1.8 celeron. Both machines have headroom to spare - I can run other apps on them without impact on folding - like photoshop, firefox, lightroom, etc.

Unless you plan on running the SMP client on this folding box as well, save money on the CPU, and buy a killer PSU instead!

 

[SatTech]

Ok, I figured I could probably squeak by on 2 cores (or maybe pick up a low power tri-core). It'll be strictly a GPU box, so no CPU clients.

Thanks for the quick answer.

 

[metallicafan]

Yep i think there are several folders around that have 4 GPUs running on 1 CPU core.

 

[Kendrak]

You fine with the BE.

When you add the 4th card (and this will be the same as declaring war against me) You might need to take a look at the CPU, but I doubt it.

You PSU will be fine up to 3 cards. I'm running a system right now with 2x GX2s and I pull 440 from the wall, take that to 80% eff = 352 watts for the PSU. (you might be able to push it with all 4 with careful monitoring)

I look forward to a battle!

 

[Tigerbiten]

I've 4x 9800GX2's running.
It pulls 900 watts from the wall.
If I drop the CPU down from a quad Phenom and remove two sticks of memory, I could probably cut to power draw a little.

If you go above 2x 9800GX2's, you will need to run XP on your box, I found Vista does not work with that number of cards.

A dual core should be fine, but you will have more overhead with a tri core.
My system only loads 3 cores on my quad Phenom.

Luck .............

 

[SatTech]

Cool, thanks for the help guys. I have a couple copies of XP laying around and was planning on using that. I'll get everything running with the dual core, and go from there. As I won't be adding the 3rd and 4th cards for a while, CPU usage shouldn't be an issue. When I get around to adding more cards, I'll watch the production and pick up a low powered tri-core if needed, and definately a bigger PSU.