Question No post/display, case fans don't spin but cpu/gpu fans do

[zaaacchh]

There's only one similar thread I've found and it was never answered. I figured I should make my own.

My specs: RTX 3060Ti, Ryzen 9 5900X, ASRock Fatal1ty b450 mini-itx mobo, 2x16Gb ram, and Corsair SF600 platinum, excluding drives/peripherals. Total wattage should be 400, which I why I went for 600.

I've triple checked that everything is seated properly and reseated. No thermal paste anywhere it shouldn't be. All cables accounted for and plugged into their respective sockets. A common problem is that the BIOS needs updated - mine came with a sufficient version (v4.80) to run ryzen 5000 series chips. The build runs fine if I swap in my old Ryzen 5 1600 though. With the new CPU, the only things that come to life are the GPU and CPU fans. Case fans strangely won't spin, and I'm forced to shut down using the PSU switch.

What could this strange case fan behavior be a symptom of? Is my new Ryzen 5900X a lemon, or am I missing something here?

 

[DSzymborski]

Have you verified that it does have an updated BIOS installed? If this is a used motherboard, it's not uncommon for a seller to claim a BIOS was updated when it fact it was not.

 

[zaaacchh]

Have you verified that it does have an updated BIOS installed? If this is a used motherboard, it's not uncommon for a seller to claim a BIOS was updated when it fact it was not.

Sorry to be slow, didn't get a notification that you replied. I did verify the version shown in the BIOS, and the mobo is new (or should be) too. Fortunately I bought a Ryzen 5 5600X to replace the 5900X and my problems are solved. I think those symptoms are that of a dead CPU, although I won't be paying for someone to diagnose it before I return the 5900X.