GA-Z87X-UD3H - LED loops from 15 to 36/32 after cold boot

[Skilly]

Hi everybody

Ever since thursday, my brother's motherboard (Gigabyte GA-Z87X-UD3H) loops LED code 15 to 36 to 32 to blank (I suppose restart) and repeat. Peripherals (All that's connected is a keyboard and mouse that work when it boots, I'll get to that later) don't receive power during that. The manual describes the codes as follows:

15 - Pre-memory North-Bridge initialization is started.
32~36 - CPU PEI initialization

I've tried reseating the CPU with no success. Now, the weird thing to all of that is that whenever I change a hardware component (what I've been doing at first is switch RAM modules around, now I've found out switching to backup BIOS, booting, force shutting down, switching to main BIOS again works too) it boots up normally. When in Windows restarting works, as does hibernation. Only when I shut it down completely (Selecting it in Windows or holding the power button) it loops from 15 to 32 again on the next boot.

Hardware:
Gigabyte GA-Z87X-UD3H
Intel i5 w/ 1150 socket
2x 8GB 1667MHz Kingston RAM (Tried them in all possible slot permutations, still looped)
Multiple different hard drives and SSDs (tried booting up with none of them plugged in, still looped)
NVIDIA GTX 760 (tried booting up without this one installed too)

Has anyone got an idea what could cause this?
Thanks

[shadowsports]

Just scratching the surface based on your description...  Did he update the primary BIOS recently?

Have your tried manually resetting the BIOS..  CLR-CMOS using jumper or switch (if equipped), battery pull, etc, then reset up from scratch.  Replace MB battery as a precaution.

When you had the CPU out, inspect the socket for bent pins.  (unlikely if you can get the system to boot normally with manipulation)

Test the memory using memtest.  If he is using BIOS profiles or aggressive OC settings, stop, remove and test for normal operation.  If resetting the BIOS and setting up again does not correct, you can reflash the main BIOS with the current (same) revision....  or use the ALT+F10 method to flash the primary BIOS from the back up BIOS.