AMD Motherboards - USB-Pcie conflict? Fm2a75 Pro4

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USB-Pcie conflict? Fm2a75 Pro4

Printed From: ASRock.com
Category: Technical Support
Forum Name: AMD Motherboards
Forum Description: Question about ASRock AMD motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=7634
Printed Date: 18 Jul 2025 at 9:23pm
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com

Topic: USB-Pcie conflict? Fm2a75 Pro4

Posted By: jsid
Subject: USB-Pcie conflict? Fm2a75 Pro4
Date Posted: 11 Feb 2018 at 1:45am

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I can't seem to get my PCIE1 slot to register the presence of a card anymore. I'm getting error B4 B3. (USB hot plug and ... CPU?)

I get the same error even when there are no USB slots occupied (except a 2.0 keyboard for input) if PCIE1 is occupied. It'll eventually POST, though it takes a while. In EFI setup, System Browser cannot see anything in PCIE1 or any of my on-board USB3 ports (I can still boot from USB3 "Win10 To Go" presumably at 2 speed, but the PCIE1 slot doesn't wake up)

PCIE slots 2-3-4 are occupied by Radeon 7950 GPUs, same that I'm attempting to plug in to PCIE1. The configuration has worked fine for years, but somethings not working now. Any suggestions?

Other specs:

PSU is OCZ 1000W 80+

CPU is A4-4000

8G PNY DDR3 (4X2)

My EFI setup is unlocked, if that opens up any useful configs or tools.