PCIe x16_2 broken on my ASUS P8Z77-V Pro?

[Peligroso]

So, I've been building a new system and it seems like the second PCIe slot on my ASUS P8Z77-V Pro doesn't work.

I have two GTX 670's that I was going to run in SLI, but the card in the second PCIe slot isn't recognized. I have tried to remove the other card, changed the cards around (as well as the wires) and both cards definitely work in the first PCIe slot but not in the second slot.

I also tried to manually set both PCIe slots to Gen2 in the BIOS but that didn't help either. Any ideas here?

Full specs:
Chassi: Fractal Design Define R4
PSU: Fractal Design Newton R3 800W
MBO: ASUS P8Z77-V Pro
GFX: 2x Gigabyte GeForce GTX 670 Windforce
CPU: Intel Core i7 3770K
Cooler: Noctua NH-D14
RAM: 32GB Corsair Vengeance
SSD: 512GB Samsung 840 Pro

 

[birthdaymonkey]

Did you install the SLI bridge that came with your cards?

 

[Peligroso]

Yes (though it came with the motherboard). I've made progress though, I took the CPU out to check for bent pins (didn't see any of those), set it back, took out the first graphics card, cleared CMOS and booted it up with only the second card in the second PCIe slot. It worked, and now after having installed drivers again and such, both graphics cards are recognized by Windows.

However, now my problem is that I can't seem to enable SLI in the nVidia control panel. I see the SLI options ("Maximize 3D Performance" and "Disable SLI" are the only two options that I can select). If I select "Maximize 3D Performance" and press "Apply", it reverts back to "Disable SLI". This is on a single monitor if that matters. Any ideas?

Edit: Worked after another reboot. All is now well and good!