Monitor cable woes, informational post

Phil
Phil
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Topic 197622

Those of you having problems getting Boinc to see your GPU, if you are using a DVI cable, switch to a VGA cable.

After beating my head against the wall for several hours on a new box, getting only GPU not found errors in the Boinc event log, I remembered a thread that said a monitor must be installed. This thread gave instructions on inserting resistors to trick Boinc into thinking a monitor was present. The resistors were inserted into the VGA socket on the GPU card.

I switched to a VGA cable and everything started working.

This is just one of many solutions to try if Boinc is not finding your GPU.

Happy Crunching!

I thought I was wrong once, but I was mistaken.

TimeLord04
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Monitor cable woes, informational post

My EVGA GTX760 is strictly DVI. It actually has two types; standard DVI, and digital DVI. I'm using the standard DVI and have had no issues. (The card also has HDMI out; however, I don't have a monitor that will accommodate that.)

What GPU are you using? Could it also have been a faulty DVI cable???

TimeLord04
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Phil
Phil
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Not a faulty cable, I thought

Not a faulty cable, I thought of that. Everything worked normally except BOINC refused to find the GPU.

Weird, I know. Just thought I would put this out there in case someone had that situation.

I have several computers that are not BOINC related that have HDMI outputs. I just use an HD TV of the desired size. Less expensive than a monitor in a lot of cases.

I thought I was wrong once, but I was mistaken.

Mike Hewson
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Ah, DVI uses differential

Ah, DVI uses differential signalling and thus would need to rely upon an AC ( floating ) ground, whereas VGA cables are double terminated ie. DC ground. So whereas a DC ground only mucks up depending on your local ( household ) ground arrangements, the AC grounds can wander about for any number of additional reasons related to the specific devices at either end of the cable. Being essentially a serial interface I think it would degrade with more than about 2 volts difference b/w the two 'grounds'.

Cheers, Mike.

( edit ) That is : there is a maximum current that can be supplied by a device at one end to 'raise/lower' the other device's ground. Thus there is no spare power to create/vary normal/valid signalling levels. It's a bit like canal locks : do you have enough water flow available ( from some pressure head ) to repeatedly even out the water levels as boats are 'switched' through ?

I have made this letter longer than usual because I lack the time to make it shorter ...

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mikey
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RE: Those of you having

Quote:

Those of you having problems getting Boinc to see your GPU, if you are using a DVI cable, switch to a VGA cable.

After beating my head against the wall for several hours on a new box, getting only GPU not found errors in the Boinc event log, I remembered a thread that said a monitor must be installed. This thread gave instructions on inserting resistors to trick Boinc into thinking a monitor was present. The resistors were inserted into the VGA socket on the GPU card.

I switched to a VGA cable and everything started working.

This is just one of many solutions to try if Boinc is not finding your GPU.

Happy Crunching!

Normally the "dummy plug" that you are talking about is only needed when you have multiple gpu's in one machine and run Windows. If there is no monitor plugged into a gpu Windows can assume you won't need it and turn it off! Meaning it won't work for Boinc, the dummy plug gives enough resistance to make Windows think something is plugged into it and then enables the gpu so you can then crunch with it.

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