USB Hotplug B4 Error on Boot

V431

Honorable
Dec 27, 2013
2
0
10,510
As of yesterday, my first build is failing to boot. The motherboard hangs on a B4 USB hotplug error, even when no USB devices are connected and all headers have been disconnected from the case. I have tried reseating and removing the GPUs, RAM, and CPU as well as reseating all the power connections to the board and resetting the BIOS, but the board still fails at the same error message.

Here is the current setup:

CPU: Intel i7-4770K
Motherboard: ASRock Z87 OC Forumla/ac
RAM: G.SKILL Ripjaws X Series 4GB DDR3 1866
GPUs: ASUS Radeon R9 290 (x2)
PSU: SeaSonic Plantinum 1000W

I was testing it by booting Xubuntu 13.10 from a flash drive. The board seemed to have trouble with the 290s even after updating to the latest BIOS. If I tried setting the default graphics adapter to PCIE in the BIOS, I wouldn't get any video from either card's HDMI, but I could still SSH into the OS. I don't know if that issue is related.

Yesterday the system just stopped booting entirely. It now stalls with the B4 USB hotplug error no matter what I do. Unfortunately, I don't have a spare PSU to try, but given the error code and the fact that all the fans (even on the GPUs) seem to be working normally, I don't think the PSU is at fault.

Does anyone have any recommendations? The other threads that I have found about the error code don't seem related to my problem. They involved problems when USB devices were attached to the system. In my case, removing all USB devices doesn't allow the system to boot. Is it time to RMA the board?
 

V431

Honorable
Dec 27, 2013
2
0
10,510
Well, after unplugging all USB devices again and then trying a different monitor and keyboard combination, the board booted normally again. GPU output is normal too. I'm still not sure what happened, but I'll assume that the problem is fixed.