Question New Build PC suddenly won't POST ?

Feb 22, 2021
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So I just built a new system yesterday.

CPU: AMD Ryzen 7 5800X
Motherboard: MSI MAG X570 Tomahawk
RAM: Corsair Vengeance 32GB (2 x 16GB)
HDD: 1TB NVMe
Cooler: Corsair iCue H150i Elite Capellix
PSU: Corsair RM750
Case: Lian Li O11-Dynamic
GPU: Reused GTX 970

I put it altogether, POST was fine, installed Windows 10, installed updates, updated BIOS, used the PC for several hours, productivity, video calls, no problem. About 6 hours later, just whilst sat watching YouTube, Windows shut down but the PC was still powered and fans were running. I powered down the system and turned it on again and now the machine refuses to POST at all.

I reseated the RAM, GPU, checked all the cables, tried with 1 stick of RAM, but no luck at all. I don't have any warning beeps or any warning lights on the onboard EZ Debug LED.

The PC was totally working fine and then after several hours, it just shut down and stopped. I was checking my temps as it was a brand new build and the CPU was stable at around 29 to 32 degrees.

Any ideas?
 
So I just built a new system yesterday.

CPU: AMD Ryzen 7 5800X
Motherboard: MSI MAG X570 Tomahawk
RAM: Corsair Vengeance 32GB (2 x 16GB)
HDD: 1TB NVMe
Cooler: Corsair iCue H150i Elite Capellix
PSU: Corsair RM750
Case: Lian Li O11-Dynamic
GPU: Reused GTX 970

I put it altogether, POST was fine, installed Windows 10, installed updates, updated BIOS, used the PC for several hours, productivity, video calls, no problem. About 6 hours later, just whilst sat watching YouTube, Windows shut down but the PC was still powered and fans were running. I powered down the system and turned it on again and now the machine refuses to POST at all.

I reseated the RAM, GPU, checked all the cables, tried with 1 stick of RAM, but no luck at all. I don't have any warning beeps or any warning lights on the onboard EZ Debug LED.

The PC was totally working fine and then after several hours, it just shut down and stopped. I was checking my temps as it was a brand new build and the CPU was stable at around 29 to 32 degrees.

Any ideas?
Reset the bios,
Unplugg psu
Pull cmos battery from mobo
Hold power button for 30s x2
Reseat cmos battery and psu cable
Boot to bios and set ram to docp. And ram timings
 
Feb 22, 2021
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So, I tested the following:

Tried another power cable (kettle lead)
Reset CMOS (both shorting and battery reseat, holding down the power for 20 seconds before powering back on)
Tried another working GPU (GTX 720)
Tried 2 working PSUs
Tried both sticks of RAM individually
Tried booting without the m.2 NVMe
Reseated the CPU
Flash BIOS via USB (latest version - v15)
Flash BIOS via USB (previous version - v14)

Still no luck. I'm totally stumped. I'm gonna try to get my hands on another CPU. Failing that, it could only be the motherboard, right?
 
Feb 22, 2021
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Never really worked out whether it was the CPU or Motherboard that was faulty. CCL Online told me that they tested the board and it POSTed fine, even though I tested with 2 different CPUs and couldn't get it to. But, they agreed to refund me anyway... And I got a refund for the open box CPU from eBay.

I'm guessing the CPU was probably the obvious issue, but who knows. Either way, I bought another 5800X from Amazon and also went for a slightly better board, the MSI Meg X570 Unify and now have a decent working system!

Signature updated! 🥳
 
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