No POST despite a compatible BIOS version

[Sprout]

I'm in the process of trying to upgrade the CPU from a Ryzen 3000 series to 5000 series on my AM4 rig and can't get it to POST. It's stuck on my mobo's EZ Debug "CPU" white LED.

 

Specs:

• MSI B550-A PRO, BIOS versions tried:
  • 7C56vAF (E7C56AMS.AF0) <- the latest available BIOS
  • 7C56vA3 (E7C56AMS.A30) <- suggested solution from this Reddit post
• CPU: Ryzen 7 3700X -> Ryzen 9 5950X
  • Cooler: Corsair iCUE H100i ELITE CAPELLIX XT
• GPU: (HP OEM) Nvidia RTX 3060 Ti / eVGA Nvidia GTX 1660 Super
• RAM: 4x 8GB Crucial Ballistix 3600MHz, CL16
  • Running without XMP, I've cleared the CMOS each time I flashed the BIOS
• Storage:
  • Some kind of Western Digital 1TB M.2 SSD
• PSU:
  • Seasonic FOCUS GM750 80+ Gold

 

Attempted Solutions:

I've tried the following various solutions on both BIOS versions to no avail:

• Disconnecting all peripherals except for keyboard, mouse, monitor (DisplayPort / HDMI)
• Booting with only one RAM stick in the DIMMA2 slot
• Booting without any RAM, GPU, nor peripherals (EZ Debug LED stays white on "CPU")

I haven't tried to swap the GPU's PCIe slot or mess with which DIMM the single-stick of RAM is slotted, but I feel like these aren't the problem since if I just swap the CPU back to the Ryzen 7 3700X it boots fine.

 

Any ideas on what else I could try or should I consider this CPU DOA? Thanks!

• No, there aren't any bent pins
• Yes, I've tried re-seating the CPU

[SpookyCitrus]

With everything you have tried, and that it works every time with the 3700X, as rare as it is I think your new CPU is DOA. Was it purchased used or new? If new is it still in the return period?

[Sprout]

I purchased it second-hand from eBay, although it was pulled from a working rig (at least I presume) so I have no reason to believe it somehow stopped working. I guess I'll try and ask the seller for details before just returning it as defective.

[SpookyCitrus]

19 minutes ago, Sprout said:

I purchased it second-hand from eBay, although it was pulled from a working rig (at least I presume) so I have no reason to believe it somehow stopped working. I guess I'll try and ask the seller for details before just returning it as defective.

Buying used can be pretty risky. Luckily Ebay has a money back guarantee. If you don't mind could you like the original listing for it from Ebay. I buy and sell on Ebay all the time and can usually tell if there are any red flags.

[Sprout]

Yeah I knew the risk haha, here's the link if you want to inspect the seller: https://www.ebay.com/itm/315058071990

[Sprout]

The seller's post shows they last had this running in their PC on 12/27/2023.

 

Tried again with the BIOS which added support for the 5800x3D -> 7C56vA9 (E7C56AMS.A90); no dice.

 

I also realized when I first swapped the CPUs I managed to get to the "VGA" LED on my motherboard, but I've never been able to get past the "CPU" LED since then. I can only think maybe I messed up the socket or pins at some point but the socket still works with my 3700X, and as far as I can see the pins look fine?

[Sprout]

For posterity's sake, I ordered a new Ryzen 9 5950X and was able to POST successfully haha