Winblows: System wont see 3rd GPU? Any advice?
Hey Guys,

I just got a new system built and it is running Windows 7 but I can't get the system to see the third GPU, at all. All three are GTX560ti models and the MSI board has 6 slots (I also have a GTS450 but no luck with it in any config either, only physical room for 3 cards at once). I cant seem to find any worthwhile help anywhere online and am stuck. 2 is nice, but 3 would be MUCH better. Any one have any suggestions or any reading material I should check out to help solve this problem or push me in right direction? (Other than the obvious - ditching Windows Smile ) I feel like I am missing something simple...

Any help is appreciated!
i never used more than 2 nvidia card on a windows machines so i cant say anything about it. from my experience with amd it was neccessary to "active" the card and sometimes it was neccessary to connect it to monitor, too. otherwise the driver disabled the card because the driver thinks "if its not used, i can turn it off to save power". dont know how this is in nvidia, but its worth a try i think.. anyone?
A couple of things to try:

1) Disable SLI if enabled.
2) Make sure you have the most updated non-beta driver.
3) Try installing your driver again and reboot.
4) Make sure that your video card is properly seated and powered.
5) Try to remove 1 of the 2 cards that is currently working and place it in the PCI-express slot that is not working (keep a total of 2 cards just to check if the PCI-express slot itself is faulty).
6) Read your motherboard manual to make sure that there are no indication about this possible problem. However since it has 6 PCI-express slots then it's probably designed to support 3-way SLI and those specific slots should all be workable together.

Can you give the exact model of the motherboard?

When you say that Windows does not "see" the third card, are you referring to the Device Manager?
1 - No SLI enabled
2 - 285.62
3 - have tried installing all three sets of drivers I hav (since I bought the GPUs over time they came with different driver discs, and I have tried latest download from nvidia)
4/5 - I have tried most of these suggestions, but not sure it was methodical enough. I will re-try this later tonight when I have time to tear thigns apart. Also trying to source a spare monitor to test Atom's theory as well.
6 - makes no mention of this issue, nor does it provide good documentation on how to enable them if multiple are in use

Using MSI Big Bang Xpower Motherboard, i7 CPU, 3xGTX560ti, 12G RAM

Yes, was referring to device manager and nividia control settings.

I will do some more work on it tonight or this coming weekend. I apprecaite the ideas you have thrown my way, will let you know how it goes...
Then I am pretty sure it's a hardware issue.
Triple check all the cables coming to card 3.
Does it gets required power from PSU ?
Does its fan spin ?
Is there some kind of switch to turn off PCI-E slots ?
Is card 3 fully inserted into the PCI-E slot, with nothing blocking it ?

Oh, did you try leaving only card 3 in its PCI-E slot ?
You know, the motherboard may be faulty.