Okay the 4th GPU (in my case) has entered the building.

After I taught myself CUDA I wrote my own program to enumerate the CUDA drivers present and was seeing 3 even though the nVidia control panel and the MMC device panel was showing 4. So it's not BOINC Manager.

I deinstalled all the nVidia drivers, rebooted and checked in the registry at

Hkey_Local_Machine\Hardware\DeviceMap\Video

to see what I had. There were 3 devices Video0, Video1 and Video2 present which were all standard VGA drivers. I then installed Forceware 185.68 and rebooted.

I now had 10 devices in the registry. I navigated down to

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video\

and looked to see what was present. Here we see a list of registry keys like

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video\(GPU ID)\0000

where there is a key for each GPU. I searched the list and for each GPU e.g.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video\{D82C4D9A-396A-4292-A538-A8F8F22FFEB5}\0000\Settings field (where {D82C4D9A-396A-4292-A538-A8F8F22FFEB5} is a GPU id)

and looked for the words NVIDIA GeForce GTX 295.

I presumed (luckily correctly) that the 1st GPUID with those words i nthe Settings field had the monitor on it. To the following 3 GPU's I added the following registry keys:-

DisplayLessPolicy DWORD 1
LimitVideoPresentSources DWORD 1

at the

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video\(GPU ID)\0000

level in the registry tree and rebooted.

Now I only have 2 monitors showing in the nVidia control panel as having my desktop on them but my own CUDA program shows 4 GPUS. I fired up BOINC Manager which still displays that it found only 3 (due to the string length being exceeded I expect) but I have 4 running GPUS.

Could you post this in the nVidia forums? I don't think there's a better way to contact them directly, except maybe if project staff would get involved.

MrS

---

Scanning for our furry friends since Jan 2002

Sure I posted over there.

I merely posted here in case anyone wants seeing the same issue. :)