Working PC after restart no longer POSTs

bobblenator · 19 Dec 2022 at 14:18

Hi all. Completely lost about the cause of my PC not booting. Built PC approx 3 years ago, been used every day since, working fine. On restarting it a couple of days ago it no longer POSTs.

Specs are:

- Asus ROG Strix B450-F Gaming
- AMD Ryzen 5 3600
- Corsair DDR4 Vengeance LPX Black 32GB (2x16GB) (3200)
- ASUS ROG Strix OC Gaming RX5700 8GB
- Seasonic 650W Prime Ultra Platinum
- Samsung 970 Evo Plus 1TB

On boot up fans start up but I get no display and no POST. Mobo debug LEDs cycle and then stops on the white (VGA) led.

Things I've tried with no success:

- Reseated all components
- Reset CMOS (by both removing CMOS battery and using reset jumper)
- Moved GFX card to other PCI slot and then back again
- Substituted in alternative PSU from old PC
- Substituted in alternative GFX card from old PC
- Tried both sticks of RAM independently
- Tried alternative monitor

I suspected perhaps the motherboard was faulty so bought a used MSI Tomahawk X570S Torpedo Max WiFi. Using this I also get fan start up but not POST. The Mobo debug LED on this one gives the red (CPU) LED.

Any ideas?

2 dead motherboards? (unlikely?)
Dead CPU? (pins all look OK, and working fine before restart)

Many thanks.

bobblenator · 19 Dec 2022 at 16:55

@jaybee kindly replied on my duplicate post (now deleted) that I should try with the motherboard outside the case to eliminate case shorts as a culprit.

I did try that with the older (Asus) mobo with the same results but not the newer (MSI) mobo.

I now have the following setup outside the case on my table.

MSI X570S motherboard
CPU
Single stick of RAM
M2 drive
PSU connected to ATX power and CPU 8pin

On startup mobo aesthetic LEDs come on but so too immediately does the red CPU LED and both remain that way.

I get the same result if I additionally connect known working graphics and associated power (with the additional effect of the GFX cards fans also starting up), but same red CPU LED.

jaybee · 19 Dec 2022 at 16:58

CPU dying is rare. Was it overclocked hard?

Dg834man · 19 Dec 2022 at 16:58

try removing the nvme see if you can get to bios, think after that you've exhausted every thing but the cpu, could also try disconnecting usb peripherals

bobblenator · 19 Dec 2022 at 17:12

@jaybee CPU was bought new 3 years ago and has never been overclocked, mostly used as office PC with occasional games. Has Corsair AIO cooler with triple 120mm radiator which all seems to be working fine still, no reason to suspect it's been overheated. Having removed from socket it all looks visually OK, no bent pins, slots back into AM4 socket on both mobos smoothly.

bobblenator · 19 Dec 2022 at 17:17

@Dg834man just tried removing the M2 drive but get the same result, immediate CPU red LED.

No USB devices, fans etc. currently connected. Stripped back to only mobo, CPU, 1 stick ram, 2 connectors from PSU (ATX and CPU 8pin).

mickyflinn · 19 Dec 2022 at 17:34

Seen plenty of Ryzen cpu's sent back to AMD so to test either borrow or buy a working cpu , Otherwise test yours in a working system.

bobblenator · 26 Dec 2022 at 13:15

Thank you. Borrowed a friend's system to test, swapped in my CPU, RAM, and GFX card into his system, and all work fine.

Seems like it has to be a problem with both motherboards, either they've failed or some configuration issue, though the fact the PC failed to boot with the asus despite no configuration changes in 3 years points more to at least that one being a filed component.

Now looking for another motherboard to swap in, and hope that resolves it!