I have two GTX 295's on my eVGA X58 mobo. I have the two set physical cards set for SLI mode. Is there a way to get the CUDA enabled Boinc to address the second GPU on each card. I found out that Boinc (Cuda enabled) does not support SLI as SLI is not a true parallel interface of the GPUs. With SLI turned off, I get 2 processing threads in Boinc. But the 295's have 2 physical GPUs on each card via a FAT Parallel interface. However, I'm getting the same CUDA processing time from a GTX 295 as I from a GTX 280, meaning only one GPU is being addressed.

BOINC should be able to find all GPUs, be it whether they are in SLI or not. But this has proven to be somewhat of a hit and miss in the earlier BOINC versions (including 6.4.5) and should be better (I dare not say fixed) in the upcoming 6.6.2

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Does Cuda scale with sli or not?

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Thanks for the response and I will try the newer version when available.

Currently, CUDA enabled Boinc only addresses the primary GPU on each card for me, and thus only addresses the cards seperately when SLI is disabled. With SLI enabled, there is one task listed and it's computations are the same speed as if there was only one 280 core. I was hoping to see all cores work together or atleast the paired cores work in parallel like the Telsa.
I don't mind this though; I wanted to see how benefical this system could be with a BOINC Project that will utilize the CUDA architecture. My other 2 systems have been with World Community Grid as it doesn't utilize CUDA just yet.

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Intel i7 940, eVGA X58, 3 GB Corsair XMS3 DDR3-1333 3-channel, 2 x BFG GTX 295 (SLI), 1 x eVGA 280 (PhysX), X-Fi Titanium PCI-E, 4 x 30GB OCZ v2 SSD (BOOT RAID 0), 150GB VelociRaptor, 2 x 22X Plextor DVD-RW/DL,SD Drive, 1200 Watt PC Power & Cooling,

I had to remove the SLI bridge as well as disable SLI and have PhysX enabled in Nvidia Control Panel for both of my 9600 GT to show up.

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I have two GTX 295's on my eVGA X58 mobo. I have the two set physical cards set for SLI mode. Is there a way to get the CUDA enabled Boinc to address the second GPU on each card. I found out that Boinc (Cuda enabled) does not support SLI as SLI is not a true parallel interface of the GPUs. With SLI turned off, I get 2 processing threads in Boinc. But the 295's have 2 physical GPUs on each card via a FAT Parallel interface. However, I'm getting the same CUDA processing time from a GTX 295 as I from a GTX 280, meaning only one GPU is being addressed.

This seems to be NVidias fault, the vista drivers are reported as not working properly...The Foldig and GPUGrid people are complaining as well.

Where does one find this version 6.6.2? I'd like to try some of this new stuff.

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All right, I asked the developer about this.

Since SLI basically combines 2 (or more) matched GPU devices into 1 logical GPU device, the system sees only 1 logical GPU and unfortunately for CUDA this means that it only has visibility to 1 physical device (not 2, 3 or 4). Disabling SLI mode for CUDA is best because it allows SETI to take advantage of each GPU on its own.

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Where does one find this version 6.6.2? I'd like to try some of this new stuff.

32bit version
64bit version

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Thanks Ageless,

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PROUD MEMBER OF Team Starfire World BOINC