Multi GPU FAH Woes

Happy · 10 Jun 2009 at 18:31

Ignore, was being thick!

I started started Multi GPU folding and am experiencing problems after about 10 mins :/

Anyway I'm running Windows 7 X64 and folding using a Q6600, 8800GTX and a 8800GT running of a HX620W PSU.

I believe they are all set up correctly but not 100%.

When only folding on the Q6600 and the 8800GTX everything was/is fine. However I added the 8800GT and when it's idling all is fine too. I have two screens one connected to the GTX the other to the GT, when I start to fold on the GT in addition to the GTX, the GTX's screen becomes really jerky and judders when moving the mouse (it skips etc) basically it becomes ludicrously slow and unsable. Yet when I pause the GT it's fine and is back to normally.

Any ideas, it does this when both cards are overclocked or at stock, I'm using the Nvidia 185.85 drivers.

Cheers

Happy · 10 Jun 2009 at 18:50

Hmmm I may have been trying to run two clients off the 8800GTX

not quite sure yet

Edit:- Yep messed up the flags, I had two running off the 8800GTX and none on the 8800GT

Biffa · 10 Jun 2009 at 22:14

XP all the way imho for multi gpu.

Mind you haven't tried with Win7 .. do you still need a monitor or dongle on each card?

Happy · 10 Jun 2009 at 22:25

Not sure, I'm running a real monitor from both cards, thought it would be easier than messing around with dummy plugs

However I'm getting appalling PPD from the 8800GT. This is with them set as high priority and not running any CPU SMP clients on my CPU. They have access to all four cores, as well.

8800GTX @ 550/1500/900Mhz (core/shader/memory)- P5911 (R8, C274, G0) 1888 points - 4800PPD
8800GT @ 650/1650/900Mhz (core/shader/memory) - P5911 (R7, C247, G0) 1888 points - 2900PPD

JonJ678 · 11 Jun 2009 at 02:04

What ppd does the 8800gt throw out if its the only one folding? If it goes up significantly, swap the cards over. I can't remember if its the weaker or the faster card you want in the primary slot, but it apparently makes a difference.

I'd love to be told why one card starves the other when they're both in the same machine, can't work it out myself.

Biffa · 11 Jun 2009 at 02:59

I'm not seeing it with my GTX260's maybe its only with asynch cards

Snapshot · 11 Jun 2009 at 06:00

I think JonJ678 has it - you want the weaker card in the primary slot as otherwise it will drag the stronger card down to its level.

Happy · 11 Jun 2009 at 09:22

It gets the same PPD if I only fold on the 8800GT as well when folding on both. Currently the 8800GT is in the bottom slot, I'll swap them around and report back.

Thanks

Happy · 11 Jun 2009 at 11:11

Right, when the 8800GT is the only card fitted in the PC in either the top or bottom slot it gets the propper PPD of around 5700PPD on a 353 pointer. However as soon as I place the 8800GTX in either the top or the bottom slot the 8800GT's PPD drops by around 2000. I have no idea why, and it's really annoying me :mad:

Any ideas?

Cheers

ChrissyT88 · 11 Jun 2009 at 11:24

I think you may be experiencing the F@H shader bug, where having two cards with different shader counts can really lower the ppd of one of the clients. Im not sure if there is an easy way around this (not something i have ever had to deal with having only single cards), but a trip to the official forum may yield a few answers.

Sorry i cannot be of more help Happy. Good luck getting the cards to work!

Happy · 11 Jun 2009 at 11:32

Ah interesting, I found one other example using google where a guy using 9800GX2s had his GTX285 crippled. I'll head on over.

Cheers

verbal · 11 Jun 2009 at 12:59

I had a 96 shader card and a 112 shader card running in the same PC and managed to get the full ppd out of both of them. I did experience low ppd until I sorted it out though. The main things seem to be putting the lower shader card in the top slot and installing the drivers from a clean start with one card in and then installing the drivers again once the 2nd card is put in. Installing the drivers with both cards in or installing the drivers only once because the 2nd card got detected when it was put in resulted in low ppd on the higher shader card.

Hope that helps

Happy · 11 Jun 2009 at 13:06

Hmm, I have the 8800GT in the top slot, and I installed the drivers when there was only one card in then again when I put the other in. I might mess around with it later.

Cheers.