Boot problems - codes B4, 9C

[briareos_kerens]

Hello everyone,

I'm having trouble with my current build.
During the first boot, the mobo hung at code B4, and then rebooted on its own. The monitor would show the ROG logo with the prompt to enter the BIOS.
I then unplugged all devices and internal USB/audio headers except the video card, and got a 9C, with the usual reboot.
I hit the Clear CMOS button on the back of the mobo, and got a code 02, plus reboot.
Moved the video card to an other PCIE slot, removed the CMOS battery, nothing; can't remember the error code but the system rebooted.
Switched BIOS, removed the video card, and got a D6 (which should be normal), and the system was on until I turned off.
Plugged back the video card, the PC booted and got the AMI screen warning me that no keyboard was present. Finally!
Plugged in an USB keyboard and...B4.
Dug up a PS/2 keyboard and...B4.
Tried to boot the PC with just the video card, B4 again.

Is there something else I can try or is the mobo I've got faulty?

Thanks for the support.

[Chino]

List your complete system specifications including the model of all your USB devices connected to it.

[briareos_kerens]

Core i7 5820k, 4x8GB Corsair Vengeance LPX 2400, Noctua NH-D15, Firepro W7000, Seasonic P-660, 2x 850 EVO (500GB and 1TB), 1x WD Black 4TB, 1x WD Black 2TB.
I've tried to connect an USB card reader (internal header, USB 2), two front USB 3 and one USB 2 headers (case), USB keyboard, mouse, USB cables to an UPS, a Cintiq, a USB hub on a Dell monitor, a printer, and two USB 3 external HDDs.
I've removed everything from the mobo and I get the B4 code without anything (including the internal SSDs and HDDs) attached.
The Firepro worked (and still works) on three different mobos, and I've reassembled the old PC with the PSU (new for this build) and all USB devices listed, and I have no problem.

[Chino]

What is the model of your Dell monitor?

[briareos_kerens]

U2410.

[Chino]

Do you by any chance have the USB cable from the monitor connected to your motherboard? If so, try disconnecting it.

[briareos_kerens]

I've already tried disconnecting everything, keyboards, mouse, internal headers, everything. I still get a B4 code.

[Chino]

Can you verify that you're seeing b4 and not 64? Users sometimes confuse the b with a 6.

[briareos_kerens]

Double checked. I've found a thread that confused 64 and B4, and it's B4 (b4).

[Chino]

1. Disconnect every single cable from the motherboard.
2. Remove all the memory modules except for the one in the DIMM_A1 slot.
3. Remove the CMOS battery and press the Start button to discharge any remaining power.
4. Wait for 5 minutes then put the CMOS battery back into place.
5. Connect the 24 pin and 8 pin power cables to your motherboard.
6. Make sure your GPU is installed properly.
7. Connect your monitor and keyboard.
8. Press the Start button.

Report back your results.