Newly built PC shutsdown randomly, fans still running, CPU LED on Mobo

[Jammy_532]

Hi everyone,

I recently built a PC (see Specs below) with all new parts and running into a problem. It (seemingly) shuts off randomly however the fans still spin and RGB is still on, so I assume the PC is still on, just lose signal to monitor, mouse, and keyboard. Furthermore, red CPU light comes on Motherboard when it does "turn off". I thought something might be overheating but after checking temperatures everything seems fine unless I’m missing something. This can be during a game, or just during web browsing like watching a YouTube video. Longest time it has been on before shutting off has been an hour, shortest time around 7 mins.

Took it to a local computer technician and he ran stress tests and said everything came back fine and that it did not "turn off" during the time he had it, although maybe he just got lucky, as it can either be a short time or long time before shutting down.

Solutions attempted:

• Reseated CPU twice
• Reset CMOS
• Disabled XMP
• Updated BIOS
• Turned off Fast start up
• Removed GPU and ran pc that way (still same outcome)
• Used different monitor
• Changed RAM around

Just looking for any potential advice or possible fixes before taking things further in terms of buying replacement parts to test (was thinking CPU first as I assume that might be where the problem lies).

Thank you!

CPU: AMD Ryzen 5 7600X 4.7 GHz 6-Core Processor
CPU Cooler: Thermalright Phantom Spirit 120 SE ARGB 66.17 CFM CPU Cooler
Motherboard: Gigabyte B650 GAMING X AX ATX AM5 Motherboard
Memory: Corsair Vengeance 32 GB (2 x 16 GB) DDR5-6000 CL36 Memory
Storage: Samsung 980 Pro 1 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive
Video Card: Sapphire PULSE Radeon RX 6700 XT 12 GB Video Card
Case: Corsair 4000D Airflow ATX Mid Tower Case
Power Supply: Corsair RM750e (2023) 750 W 80+ Gold Certified Fully Modular ATX Power Supply
Case Fans: 4 Thermalright TL-C12C-S X3 66.17 CFM 120 mm Fans

 

[Alex Glawion]

Did you make sure you've taken off the plastic cover from the CPU cooler's underside? Also check your temps to make sure the CPU isn't overheating as this sounds like an over temperature shutdown.

Also make sure you've connected all of the CPU Power cables from the PSU.

 

[Tim D]

Have had problems with boards earthing out because not on spacers from case, some cases are much better than others. Check there is air space from any solder, pass some paper/card underneath perhaps. Conversely sometimes you need a good earth through the mount screws and bosses and it has been known for boards to not have a clean contact earth around this local point. Rare but not unknown.
Fixed an Asus ROG Strix b450 f2 Gaming which was shorting randomly through insufficient space, last year. No damage hade been done to m/board.
Similar symptoms to those you describe, seemingly random.

Was not the BIOS even though Asus had issued yet another one for that board for the umpteenth time.... seems pretty stable now tbh.

 

[ennicola]

I had a similar problem and tested it piece by piece only to find out the power supply was faulty, have you tried another one?