I'm losing my mind over this, but here goes. Brand new Gigabyte G1 X99 Gaming Wifi mobo, New i7-5820k cpu, new Corsair Vengeance 16gb (4gbx4) 2800 ram with New OCZ Vertex SSD 120gb.
So upon install, My 2nd GPU (EVGA GTX 580s) wasn't being detected. The motherboard was revision 1, and had the F4 bios. Thought the issue was me running Windows 10 tech preview, so I switched back to my Windows 7 pro. Still no luck. Tested both cards in slot #1 solo and both worked. Then tested both cards in Slot 1 and 4, both detected together and sli is an option. Slot 3 works with my 9500gt. Tried again with slot 1 and 2, slot 2 detects nothing. All drivers removed, wiped with driversweeper, and reinstalled. Nothing.
Next I tried to update the bios. Couldn't sworn I saw an F8, but had no luck installing (bad image) so went with F7 and flashed fine. Reinstalled the OS (win7) and nothing. Poked around the bios, but only thing I saw (unless I missed something) was setting pcie from auto to gen 1,2,3. Set the bios to use pcie 2 as the display output.. but never got a signal. Wiped, tried again, got frustrated and guessed a defect. RMA'd it the next day to Newegg, who sent a new board.
Guessing they never even tested it, because I just got my new one, and same issue. Same troubleshooting steps and I simply can't get the second slot to work. The manual says that slot #3 is disabled with a 5820k, and that slot #4 should only be used for 3 way sli, and specifically states to use slot #1 and #2 for two way sli, for any cpu. I'm at a loss. I now have 3 GPU's up and running, in slots 1, 3 and 4. But slot 2 still detects nothing. Maybe someone has some troubleshooting steps to try and some other advice? I'm pretty sure it isn't hardware, as it's the second mobo, and both cards work fine when I toss em back into my x58 board, and even tested my 9500gt just to be sure.
Best Answer
I got it working. Not sure exactly what was the cause but likely the bios update to F8 I was on F5 so I am not sure which Update it was that fixed it. All I did was I loaded the 2 gpu's in slot 1 and 2 with the SLI connector then I did the BIOS update to F8. On loading of Windows and it did take a while for windows to load some configurations. Now my GPU runs in slot 2.
Now my last item which shouldn't be to bad is getting Windows to recognize these cards as running in 2way SLI.
Tried uninstalling drivers and reinstalling drivers. Using add remove programs. Thinking I may need to remove the drivers from the Device Manager then reload them. Windows always reloads the drivers on restart so I don't think it is getting a fresh driver install and from what I read thats what is needed to get SLI going and have the Control Panel finally give me that option.