Hi Steve - dummy plug in place - monitor seen - just doesn't want to run WUs on it.
Task details show it is seeing only one CAL device.....

Hi Steve - dummy plug in place - monitor seen - just doesn't want to run WUs on it.
Task details show it is seeing only one CAL device.....

You can enable/disable Crossfire through the CCC (or the ATI Tray Tools, whatever you are using) even on a X2 card. So you should check if it is enabled or not.

Do you have a X2 with 4 DVI connectors? In such a case you can use two dummy plugs (or one dummy plug + a monitor) to use both GPUs even with crossfire disabled (is actually better/more efficient/faster than the crossfire solution). The problem is that on a normal X2 with only 2 connectors both are attached to the same GPU.

Hello CP. I have the 4870X2 with 2 DVI ports - the menu options for Crossfire don't even apprear in the CCC - guess the card is Crossfire only.

Hello CP. I have the 4870X2 with 2 DVI ports - the menu options for Crossfire don't even apprear in the CCC - guess the card is Crossfire only.

Have you checked that it is enabled with a third party tool like GPU-Z?

Yes, it is enabled - as shown under GPU-Z.
Whilst I can run 4 WUs - wall clock time is approximately twice a single 4870 WU time - leadning me to conclude only a single GPU is being used from the pair.

Puzzling - my 2Gb 4870X2 will get thru less WUs than a much cheaper 513Mb 4870.

Yes, it is enabled - as shown under GPU-Z.
Whilst I can run 4 WUs - wall clock time is approximately twice a single 4870 WU time - leadning me to conclude only a single GPU is being used from the pair.

Puzzling - my 2Gb 4870X2 will get thru less WUs than a much cheaper 513Mb 4870.

That is really strange. Btw., you don't need to raise the n parameter, as it is per GPU. The task details will show you if it recognizes more than one GPU. I assume it's this Core2 Duo? As you use Vista have you tried another driver version? I tried Crossfire once with 8.12 and it worked, but it was XP64, so who knows?

...... Yes, that's the correct host. Will try another set of drivers and see whather it is the XFX implementation that is awry.

Reinstalled 8.12 from another vendor - no difference - GPU-Z says Crossfire active - ATI Overdrive sees both GPUs of the 4870X2 - but one is inactive.

Will try a couple more things then RMA it......

Reinstalled 8.12 from another vendor - no difference - GPU-Z says Crossfire active - ATI Overdrive sees both GPUs of the 4870X2 - but one is inactive.

Will try a couple more things then RMA it......

Actually I meant you should try let's say Cat9.5 (with the dll rename stuff) and see what happens.

...... OK. I'll give that a go.

Thanks,
P.

CCC 9.6 loads the card on both GPUs with MW WUs - albeit at a reduced frequency (507/500MHz)on the second GPU - which is odd. .DLL files copied & renamed.

More digging required.

Thanks CP - you have been a great help.

I can see that on my dual 4850X2 as well. GPU-z reports one GPU idle, but as far as I can see, it's not correct. All gpus are active.

When you start mw@home with the commandline "n2 x1" setting, it'll start 6 tasks that run smoothly.

I tried this with "n2 x1..4" settings and always had the same performance. Lower than without the "xn", so manually disabling one GPU (the one that's reported to be idle) reduced the speed compared to all four gpus being loaded. I guess it's just a mis-reading caused by the drivers.

Long story, short end.... enable crossfire and you get full performance.

Besindes... Try "n1" ... The workunits are longer these days and you'll avoid multiple tasks being copied to all gpu memory banks (got that hint from ClusterPhysik)

It increased my performance when I went to "n1"

Cheers,

Sysfried

CCC 9.6 loads the card on both GPUs with MW WUs - albeit at a reduced frequency (507/500MHz)on the second GPU - which is odd. .DLL files copied & renamed.

More digging required.

Thanks CP - you have been a great help.

That means it's running 1 GPU in 3D mode, the other in 2D mode.

Try using ATi Tray Tools, from Guru3d.com (not ATi tools, TRAY TOOLS :))

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