Question CPU / Motherboard not working

zwelch121

Reputable
Feb 9, 2018
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Hi all,

TLDR: Used my Ryzen 7 1700X CPU to boot into a ASUS x470 Aorus Ultra Gaming motherboard so that we could update the BIOS to a newer version that supports the Ryzen 9 3900X Processor. Updating the BIOS on the ASUS motherboard fixed the issue and now it will boot with the Ryzen 9. I placed the Ryzen 7 1700X CPU back into my ASRock AB350 motherboard and now it won't boot and black screen.

Current build:
BOARD: ASRock AB350 Pro4
CPU: Ryzen 7 1700X CPU
MEMORY: Corsair Vengeance DDR4 memory 2x8 GB kit (CMK16GX4M2A2666C16) ver 8.31
MEMORY: Corsair Vengeance DDR4 memory 2x8 GB kit (CMK16GX4M2A2666C16) ver 5.31
GPU: XFX Radeon R5 220 625MHz
PSU: Corsair RM 750x

I used the CPU out of my computer to put into a friends computer to update the BIOS to a newer version on the ASUS x470 Ultra Gaming motherboard. After updating the BIOS, his PC booted fine, but now my computer will not boot! Basically, all we did was remove CPU from ASRock mobo, insert into ASUS mobo, update BIOS, remove CPU from ASUS mobo, insert back into ASRock mobo, and now my computer will not boot.

After long time of troubleshooting this issue I have it narrowed down to either the CPU or the motherboard. (or maybe the BIOS chip?). Troubleshooting steps I have done:
1. "No POST", "system won't boot", and "no video output" troubleshooting checklist.
1.5. Memory - tested memory on different motherboard and it works fine and boots. Memory is a known good.
  1. PSU - tested PSU by taking a digital volt meter and testing every pin for the correct voltage. All checked out good. Tested CPU power connector and this checked out good.
  2. GPU - tested my GPU on different computer and this worked fine.
  3. Speaker - Bought a buzzer and plugged into motherboard, if I try to boot with no memory I get three beeps. When I boot with memory I get NO beeps.
  4. Tried resetting the BIOS and I Still get the same issue.
  5. My RAM is seated properly.
  6. Tried every single DIMM slot. Just about every combination you can think of. 1 stick in A2 and 1 in B2. 1 stick in A2. (for all sticks). 1 stick in A2 and B2. You name it I tried it.
After eliminating the above a went further and bought a POST Troubleshooting card (UEFI BIOS DEBUG ELF) - When I plug this into the TPM chip and boot with the memory and CPU, I get error code (21) which indicates BAD DRAM. But I know the DRAM IS GOOD Because the same RAM works perfect on a different computer. I found a pretty good article of someone who (sounds like ran into the same issue here), and basically at the end of this article the person said that it was the memory controller on the CPU and a new CPU fixed the issue.
https://forum.level1techs.com/t/list-of-dr-debug-bios-codes/114364

What do the experts of the Internet think this issue is more likely to be, bad motherboard, CPU, or could it even be the BIOS? The symptoms are is that it is behaving like the CPU knows the memory is there but the two are unable to synchronize the speed properly. I had an issue in the past with this motherboard where I had to create a custom memory profile for all four DDR4 memory sticks to work. I bought an Athlon X4 950 (AD950XAGM44AB) for testing and this CPU REALLY does not work when I plug it in. It gets stuck at A8, so the CPU I bought may be a bit too old even though it is listed on the CPU Support List. I was hoping it would help me eliminate whether or not it is the CPU or motherboard.

Thank you.
 
Jul 14, 2021
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my guess is the problem is with the CPU? have you tried inserting a another CPU and check whether your motherboard and the system works properly ?
 

zwelch121

Reputable
Feb 9, 2018
5
0
4,510
0
my guess is the problem is with the CPU? have you tried inserting a another CPU and check whether your motherboard and the system works properly ?
Well, I tried inserting the Athlon X4 950 CPU (which is on the CPU support list) and the system stops booting immediately when I power it on. I get error code A8 in this case. I think the CPU I tried might be a bit too old I would have to get a different CPU.
 

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