2 9800GX2, may I run 4 cores?

Questions and comments regarding the GPU2 client running on a nVidia GPU that supports CUDA.

2 9800GX2, may I run 4 cores?

Postby AE7 » Fri Aug 01, 2008 9:14 am

I am building my new PC and I just ordered up two 9800GX2 after the price went down yesterday. Can I run four GPU2 cores at once with this setup?

Thanks
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Re: 2 9800GX2, may I run 4 cores?

Postby toTOW » Fri Aug 01, 2008 10:42 am

Thread moved to nVidia forum.

Yes you'll have to install 4 GPU2 clients, disable SLI, and enable screen outputs for each "half board" ...

I suggest you search around the nVidia forum ... there might be someone else who already explained how to setup this kind of boards.
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Re: 2 9800GX2, may I run 4 cores?

Postby ahu » Fri Aug 01, 2008 11:13 am

I have done this with my two factory overclocked XFX boards. I get over 20 000 total PPD (5184 per board). This is with Windows Server 2003.

I had problems with Vista though. For Vista, you have to have screen extended to each GPU output, which is VERY awkward in this case. Still for some reason I got only about 2500 PPD per GPU, I wonder why?
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Re: 2 9800GX2, may I run 4 cores?

Postby AE7 » Fri Aug 01, 2008 11:16 am

Okay... I knew I would have to install 4 clients and also disable SLI... But, what I don't, how does this dummy plug trick work? And would I need the dummy plugs if I were to fold on XP instead of Vista?

I have searched around this forum and I found this chart:
Image

I question this for the 9800GX2, they only have one core running on it so that's not the card's actual PPD.

Thanks
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Re: 2 9800GX2, may I run 4 cores?

Postby ahu » Fri Aug 01, 2008 11:21 am

No need for dummy VGA's in XP :)

Yes, the chart shows only the PPD for one GPU core.
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Re: 2 9800GX2, may I run 4 cores?

Postby legoman666 » Fri Aug 01, 2008 1:07 pm

AE7 wrote:Okay... I knew I would have to install 4 clients and also disable SLI... But, what I don't, how does this dummy plug trick work? And would I need the dummy plugs if I were to fold on XP instead of Vista?

I have searched around this forum and I found this chart:
Image

I question this for the 9800GX2, they only have one core running on it so that's not the card's actual PPD.

Thanks


When I made that chart, I doubled the PPD/$ for the 9800GX2 to reflect that it has 2 cores but I didn't double the PPD number itself. So you are correct.
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Re: 2 9800GX2, may I run 4 cores?

Postby AE7 » Fri Aug 01, 2008 1:25 pm

legoman666 wrote:
AE7 wrote:Okay... I knew I would have to install 4 clients and also disable SLI... But, what I don't, how does this dummy plug trick work? And would I need the dummy plugs if I were to fold on XP instead of Vista?

I have searched around this forum and I found this chart:
Image

I question this for the 9800GX2, they only have one core running on it so that's not the card's actual PPD.

Thanks


When I made that chart, I doubled the PPD/$ for the 9800GX2 to reflect that it has 2 cores but I didn't double the PPD number itself. So you are correct.


Okay... I didn't/don't mean to just pick at your chart, I was just hoping that wasn't the PPD for both cores. If it had been, I was not gonna be happy. :? Btw, the price for a 9800GX2 went down to $285.

I plan to have 2 500GB HDD's for Vista and another 500GB HDD for XP. I am gonna fold in XP because of the dummy plug issue and XP uses just a bit less resources so it might yield more. I disable SLI, install 4 cores, but, how do I make each core run on a specific GPU?

This is my first SLI rig... Do I have to remove the SLI bridge to disable SLI or can I do it with software? And will XP save settings when I disable SLI so that it won't disable it in Vista?

Thanks a ton guys
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Re: 2 9800GX2, may I run 4 cores?

Postby Fadamor » Fri Aug 01, 2008 2:49 pm

AE7 wrote:I am gonna fold in XP because of the dummy plug issue and XP uses just a bit less resources so it might yield more. I disable SLI, install 4 cores, but, how do I make each core run on a specific GPU?
FYI, XP will use 100% of a core per GPU client, while Vista will only use about 16% of the core per client.

There is an environment setting that allows you to specify core affinity for each GPU client. The setting is "set NV_FAH_CPU_AFFINITY=x" where x equals a bit-mask identifying the desired core:
1 = Core 0
2 = Core 1
4 = Core 2
8 = Core 3

You would need to change this environment setting prior to running each GPU client (otherwise all subsequent clients will have the same affinity as the first). I ensured this by creating a batch file for each GPU client that sets the appropriate core affinity, then runs the client from the appropriate data folder.
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Re: 2 9800GX2, may I run 4 cores?

Postby Bernie64 » Fri Aug 01, 2008 4:14 pm

Can you post the power consumption of the system when running 4xFAH on the 2 GX2's?
4x9800GTX pulls about 700watts.

thanks
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Re: 2 9800GX2, may I run 4 cores?

Postby toTOW » Sat Aug 02, 2008 12:11 am

To be accurate in your chart, you should add ~3 years of power costs for each GPU ... ;) (considering your GPU will be amortized after 3 years)
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Re: 2 9800GX2, may I run 4 cores?

Postby grumpydaddy » Sat Aug 02, 2008 12:27 am

Given that in Vista the percentage of one core used is small (compared to XP that I use) and assuming the use of a 4 pcie slot motherboard is it then possible to Fold 4*9800gx2s equiv. to 8 singles because if so the gx2 is still a 280 beater by some margin
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Re: 2 9800GX2, may I run 4 cores?

Postby Fadamor » Sat Aug 02, 2008 4:23 am

Ugh. That would be 8 PCI-E power connectors. :( That's a lot of 12V current being sucked up!
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Re: 2 9800GX2, may I run 4 cores?

Postby grumpydaddy » Sat Aug 02, 2008 12:58 pm

Fadamor wrote:Ugh. That would be 8 PCI-E power connectors. :( That's a lot of 12V current being sucked up!


Yep...normally I have all these "spare" cables on the psu that need hiding...would be good to see most connected :wink:

I'll have to see what the current draw would be too cos I've only got 72A to play with :?:
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Re: 2 9800GX2, may I run 4 cores?

Postby leexgx » Sat Aug 02, 2008 10:55 pm

i got 3 9800GX2 pulling 655w from the wall (PSU is 86% efficient at the load i am useing, so whats that 600w system load?) on an 240v line
this is on an AMD64 X2 (dual core) @ 2.8, windows 2003 x64 (i have 1gb free ram if this was server 2003 32 LOL (6 GPUs each 512mb = 3gb ram set aside)

i not pluded my 4 other hdds in yet but i guess that may put the load to 700W (TK Toughpower 1200W) i got room for one more i guess as you can buy PCI-E ribbion cable so i could use the last PCI-e port only problem with that is what rail to use (the 1500w ver has 8 native PCI-e power connctors) i got to keep an eye on the power draw as got an air con running of the same plug (be pulling over 2kw when it kicks in) wish i had more then 2 sockets in the room

updateing hardware info
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Re: 2 9800GX2, may I run 4 cores?

Postby leexgx » Sat Aug 02, 2008 11:12 pm

wish the DO NOT lock onto cores worked (you made it final none beta now but not fixed that option)

what option set NV_FAH_CPU_AFFINITY=x sets it to use all cores
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