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I want use the motherboard as the primary display adapter and my NVIDIA graphics card as a dedicated CUDA processor. My first thought was to simply plug the monitor's VGA cable into the motherboard's VGA port and hope the BIOS was smart enough to use the on-board video as the display adapter when it booted. That didn't work. The BIOS must have detected the NVIDIA card and continued to use it as the display adapter. The next thing I looked for was a setting in the BIOS to tell it "don't use the the NVIDIA 560 as the display adapter, use the on-board video as the display adapter". I search through the BIOS and the Web, but either this cannot be done or I cannot figure out how to do it. The mobo is a BIOSTAR TH67+ LGA 1155. Windows 7 OS.

RESULTS SUMMARY (from answers provided below) Enabling the Integrated Graphics Device (IGD) in the BIOS will allow the system to be driven from the on-board graphics even with the graphics card connected to the system bus. However, the graphics card cannot be used for CUDA processing. Windows will not enable graphics devices unless a monitor is attached to them. The normal driver stack cannot see them. Solution: use Linux, or attach a display to the graphics card but do not use it. The Tesla cards (GPGPU-only) are not recognized by Windows as graphics devices, so they don't suffer from this.

Also ,a newer BIOSTAR motherboard, the TZ68A+, supports the Virtu drivers which permit sophisticated simultaneous use of the graphics cards and on-board video.

Compass
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ahoffer
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3 Answers3

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I believe this will happen automatically as the native video won't support CUDA. After installing the SDK, if you run DeviceQuery, do you see more than one result?

M. Tibbits
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  • I'm pretty sure that I would only see one result because the H67 motherboard video adapter is not a CUDA capable device. But that's OK, because I only want to use the mother-board's video adapter to drive the monitor; I want to use the NVIDIA card as a dedicated CUDA device. – ahoffer Jul 16 '11 at 14:01
  • Correct. And this the behavior you desire? – M. Tibbits Jul 16 '11 at 15:38
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I believe h67 allows coexistence of both integrated & dedicated GPU. Check out Lucid Virtu here http://www.lucidlogix.com/driverdownloads-virtu.html it allows switching GPUs on the fly. But I don't know if it affects CUDA device query. I never tried it on my rig, because its x58, I just heard it from tomshardware. Try it out and let us know. Lucid Virtu is definitely worth a try, its free, and it can cut you electric bill.

HooYao
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  • Lucid's Virtu looks like a really interesting product. I would like to try it. I poked around on the Web a bit and it looks like only the BIOSTAR motherboard that supports it is the TZ68A+. I'll send an email to their support group and ask if also works on the TH67+. Thanks for the pointer! – ahoffer Jul 17 '11 at 14:38
  • I have news from BIOSTAR: "...TH67+ does not include Lucid Virtu; only our Z68 motherboards will support Virtu." – ahoffer Jul 19 '11 at 03:44
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Looking at the BIOS manual (.zip), the setting you probably want is Chipset -> North Bridge -> Initiate Graphics Adapter. Try setting it to IGD (Integrated Graphics Device).

Jesse Hall
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  • I was able to use the IGD by changing the BIOS settings. Thank you. Unfortunately CUDA deviceQuery fails to detect any CUDA capable devices, so the BIOS must somehow be disabling the NVIDIA card. Too bad. – ahoffer Jul 20 '11 at 04:15
  • Windows won't enable any graphics devices that don't have a monitor attached, so the normal driver stack won't see it. You can use Linux, or attach a display and just not use it. The Tesla cards (GPGPU-only) don't appear to Windows to be graphics devices, so they don't suffer from this. – Jesse Hall Jul 20 '11 at 19:35