DVI + DP, doesn't boot

[co0ldown]

Hello, I have a weird problem. I'm trying to boot with 2 monitors connected to my computer (i5 3570k, z77 ud3h, 2x4gb vengeance 1600mhz, msi 7870 tf3, silverstone ST75F-P 750W) via DP and DVI. But it won't simply boot, it just starts and then shuts off 5 sec later and then tries to start again. I can start it with only one monitor connected via DP or DVI and it works just fine. I have the latest drivers (12.10) and I've tried reinstalling them. And no, I don't have my cables connected to my motherboard.
Any suggestions? It's really annoying when I have to unplug one cable to boot.

 

[cl-scott]

A bit of a WAG, but I know on some cards the DVI and DP ports share some internal circuitry when in dual-link mode. So if you have a DVI port set to dual-link mode, it will disable one or more of the DP ports. Why that would then cause the system not to boot as opposed to just having one monitor not work is kind of where my idea falls down, but it's at least a possibility.

 

[co0ldown]

I've noticed, it's not the monitors fault, it just started to have this problem when I got my second monitor. It boots for 5 sec and the BIOS (UEFI) looks really weird, no artifacts but it just says "gigabyte uefi interactive bios" or something along those lines, at the top of the screen and then it shuts off. This only happens when I've had my comp turned off for a while, usually over night. I read about "boot loops" but that doesn't happen on z77, only on the z67 and z68 (I think that's what I read).