Using more than one GPU card.

Post by **Megacruncher** » Tue Sep 09, 2008 11:38 pm

As the owner of an Asus P5B-Deluxe Mobo with 2 PCI-E slots I thought I'd experiment.
Once I'd got a decent PSU in place I installed my nice new 9800GT and a rather older 8600GTS together.

I installed the CUDA drivers. Bingo! After a restart device manager showed the 2 of them in place and working. :)
I upgraded to Boinc 6.3.10. Again it worked but from the messages BOINC only recognised the 9800 GT
09/09/08 22:51:21||CUDA devices found
09/09/08 22:51:21||Coprocessor: GeForce 9800 GT (1)

I attached to PS3Grid and it's running wonderfully stable but only on instance. Hardware monitor however shows that both GPU Cores are quite warm @ 57deg.

So glass half full time - any advice on how to fill it?
(I'm using 64-bit Vista.)

Post by **FlyingfocRS** » Wed Sep 10, 2008 12:15 am

I always thought it had to be matched pair of cards in each slot?

Post by **Megacruncher** » Wed Sep 10, 2008 12:48 am

I think that's true for SLI gaming purposes but not this check this out. From the rest of that thread it all seems possible but unreliable.

Post by **rowpie** » Wed Sep 10, 2008 2:14 pm

when running multiple graphics card the same rules as most of comptuer hardware apply. best to run matching parts.

when multiple cpu use the same model.

use the same memory capcity and type in each slot

use the same graphics cards when running several.

in theory all of the above works with unmatched components however you normally end up with a bigger head ache than performance.

Ben · Post by **Ben** » Wed Sep 10, 2008 7:50 pm

I'm not sure, but at a guess I think the 8600GTS will not work because it is only a CUDA 1 card, whereas the 9800GT is CUDA v1.1 or v2 (i can never tell).

But I think that's where your problem lies as the 8600GTS will sit there not doing anything as it cannot handle the CUDA 2 calculations, whereas the 9800GT can.

Hope this helps

Post by **Megacruncher** » Wed Sep 10, 2008 9:39 pm

I've had it in other setups and the 8600GTS does run, albeit slowly (42 hours). I'll try doubling up my 2 9800s & see what happens.

I also acquired an 8600GTS AGP card. Do they work or does it have to be PCI-E?

Ben · Post by **Ben** » Thu Sep 11, 2008 7:28 pm

Megacruncher wrote:I've had it in other setups and the 8600GTS does run, albeit slowly (42 hours). I'll try doubling up my 2 9800s & see what happens.

I also acquired an 8600GTS AGP card. Do they work or does it have to be PCI-E?

Was the 8600GTS working before they went to application version 1.43? As im pretty sure when 1.43 came out it would have stopped the 8600 Range from running due to the new CUDA 2 programming features which they cannot handle.

As for the AGP, i think BOINC doesn't mind what connection they are in as long as it is a compatible Nvidia card. Although PCI-E is much quicker and may improve WU times, although i can't be 100% sure.

Post by **Megacruncher** » Fri Sep 12, 2008 10:24 pm

The 8600 worked straight after they got the windows version to work properly if thats any help.

I tried the 9800s in the same machine. The system recognises them both but not Boinc.

Ben · Post by **Ben** » Fri Sep 12, 2008 11:19 pm

Are you running BOINC Manager 6.3.8 or 6.3.10?

Also, try detaching from the project and re-attaching as sometimes this can solve some of the problems. The 8600 would have worked after they brought out the windows application, however since application 1.43 i think it would have stopped working as it can't support the newest CUDA drivers.

Post by **Megacruncher** » Sat Sep 13, 2008 12:24 am

The 8600 would have worked after they brought out the windows application, however since application 1.43 i think it would have stopped working as it can't support the newest CUDA drivers.

Sorry I must contradict you there, but in a positive sort of way! :) In the course of swapping about cards tonight I put the 8600 into the machine where the second 9800 had been. It ran fine if rather slowly managing 1% in just under half an hour. I've got the 9800 back where it was and it has continued the WU begun by the 8600 without complaint.

I'll try the detatch-re-attatch trick another night. I am of course running 6.3.10.

Ben · Post by **Ben** » Sat Sep 13, 2008 7:04 pm

Sorry, my mistake. For some reason i thought the 8600 series had been excluded since the new CUDA drivers were required. Good to hear it can still work fine.

Post by **CycloneRanger** » Mon Feb 23, 2009 1:23 pm

I'm also running an 8600GT and had come here hoping to find out why it was so "erratic". It seems to work, but reluctantly. I'm guessing that the answer - if I interpret this thread correctly - is that it has not quite enough 'goomph' to manage the tasks. ['goomph' is a technical term.

]

Post by **jockmacmad2** » Mon Feb 23, 2009 2:17 pm

The 8600GT has 32 Stream Processors and I believe GPUGrid reccomends 64 in order to hit the short deadlines for returned units. The 32 may manage some units but not others which may be the erratic behaviour you mention. Thus meaning it has 50% of the required

'goomph'

Post by **Reeltime** » Mon Feb 23, 2009 2:56 pm

CycloneRanger wrote:I'm also running an 8600GT and had come here hoping to find out why it was so "erratic". It seems to work, but reluctantly. I'm guessing that the answer - if I interpret this thread correctly - is that it has not quite enough 'goomph' to manage the tasks. ['goomph' is a technical term. ]

Would it work on the likes of Milkyway?

Post by **ianmbaker2** » Mon Feb 23, 2009 5:21 pm

From what I can gather on the MW site, the MW app uses the ATI graphics cards, rather than the NVidia supported CUDA interface. So it'a OK with new'ish ATI card ( 3xxx nad 4xxx series) but doesn't run on NVidia cards.

Ian

Post by **jockmacmad2** » Mon Feb 23, 2009 8:06 pm

Yup ATI and it's a little more restrictive than you mentioned it's 38xx and 48xx.

The Scottish Boinc Team

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