PC keeps rebooting after unexpected crash

[namegoeshere]

As the title says, I am having issues with my pc but I'm not sure if its a hardware problem or a software problem.

I tried:-Changing the ram to another slot but it failed
-Putting one stick of ram on the motherboard but it failed
- Using another PSU it failed
- Running Memtest but my memory passed
- Using another hard drive, it worked for a day and it failed
- Making a fresh install of Windows and it failed
- Using other SATA cables but it failed
- Using another Optical Drive but it failed
- Starting up the PC using the motherboard's On button
- Disconnecting all the external devices and it failed
- Checking the PC's temperature but it is a stable 30 Celsius

So my guess is the motherboard, any idea?

 

[Bromeh]

Motherboard would be the first guess but did you think about the power supply ?What brand is it and how much power is in there. I can make a system fail one day and be okay the other day. Try with a really good psu (100w over what you have now + good brand) and see how it goes. If it's failling with that one, i would go for the motherboard.

- The Brownie

 

[namegoeshere]

Motherboard would be the first guess but did you think about the power supply ?What brand is it and how much power is in there. I can make a system fail one day and be okay the other day. Try with a really good psu (100w over what you have now + good brand) and see how it goes. If it's failling with that one, i would go for the motherboard.

- The Brownie

So it is the motherboard because, I have an AX750 and the other PSU was a CX700. Obviously Corsair is a good brand.
Also, THANK YOU so much for your help.

 

[namegoeshere]

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