Question B450 Pro4 not booting with USB plugged in

Jan 17, 2020
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Components:
Asrock B450 Pro4 (3.90)
Amd Ryzen 3600 (Stock Cooler)
Corsair Vengeance LPX 16GB (2x8GB) (CMK16GX4M2B3200C16)
Palit GTX 960 4GB
700 Watt be quiet! System Power S6 (PSU)


Hey guys, i need help before i return my (maybe faulty) B450 Pro4.
I checked every connection twice and built PC's at my job, so yes everything is plugged in the right way.
Everytime my keyboard or anything else is connected to the USB-Ports it wont boot. CPU-Fan, PSU-Fan, and Graphicscard-Fan spins but not the Case-Fans.
I cant power off while holding the power button and the beeper says nothing.
If i unplugg the USB devices it starts up normaly.
So is my B450 Pro4 faulty? Should i return it or is there a fix (maybe comming).
Any BIOS settings that could fix my problems?

Thanks in advance :)
 
Jan 17, 2020
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If you disconnect the case front I/O USB cables from the motherboard, does the issue is still present when the USB is connected to the motherboard USB ports?
The issue is still present that way. I unplugged the USB2.0 and 3.0 cables from the motherboard.
 

Third-Eye

Distinguished
The issue is still present that way. I unplugged the USB2.0 and 3.0 cables from the motherboard.
You may have to pull the motherboard out and check there nothing touching the board that shouldn't be. Make sure you didnt mess up the I/O shield on the back. Run the board outside of the case on a short box like the motherboard box to see if it's an electrical grounding issue.
 
Jan 17, 2020
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You may have to pull the motherboard out and check there nothing touching the board that shouldn't be. Make sure you didnt mess up the I/O shield on the back. Run the board outside of the case on a short box like the motherboard box to see if it's an electrical grounding issue.
So finally i had time to test it. It's not a grounding issue. I put it on the Box (with the padding underneath) like you recommented and it's the same issue as before. I even brushed the Board before powering it to make shure no dust could be the problem
 
If you tested the motherboard outside the case with basic components and it doesn't boot then it appears to be a faulty unit.
Make sure to test with just the CPU, GPU and one stick of RAM on slot A2 (2nd from CPU) and no disk.
Make sure all power connectors were connected properly.
If you haven't, reset the BIOS by removing the CMOS battery for 5 minutes.
Make sure to disconnect power from motherboard and video while working on motherboard or power cord from PSU.
The motherboard might cycle on and of for several minutes...be patient.
How do you know the BIOS version is 3.90?
 
Last edited:
Jan 17, 2020
9
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If you tested the motherboard outside the case with basic components and it doesn't boot then it appears to be a faulty unit.
Make sure to test with just the CPU, GPU and one stick of RAM on slot A2 (2nd from CPU) and no disk.
Make sure all power connectors were connected properly.
If you haven't, reset the BIOS by removing the CMOS battery for 5 minutes.
Make sure to disconnect power from motherboard and video while working on motherboard or power cord from PSU.
The motherboard might cycle on and of for several minutes...be patient.
How do you know the BIOS version is 3.90?
I updated the Mainboard from 3.6 to 3.9 myself (under 3.6 it didnt work either). I tried already like you said with only the least possible connections. Also with only one dimm in a2. With keyboard plugged in i could run it hours without something appearing (waited for like 30mins nothing happened) also i cant Power it off Holding the power button. So i send it back.
 

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