What could be the problem with the computer?

Question

Power Supply

Worth PSU DEXP DNP-450 400W I almost did not find information on the Internet, I sin on it. Recently, crashes have begun in games and when playing video. Windows sometimes does not load (sometimes you have to reinstall), the video card crashes with a driver error (stopped responding and was restored), sometimes the nvidea driver crashes error 3.
Components:
Athlon x2 860k
8gb ram
MSI Geforce GTX 750Ti StormX
1Tb HDD Toshiba

Answer 1

memtest from boot media for 12 hours. There will be errors or freezes - probably iron. It will not be - perhaps the software is to blame.

Answer 2

Windows writes in the logs? What is the temperature of the processor (bios) and what is the temperature of the video card (nvidia inspector)?
Trite, but did you try to update the video card driver?

Answer 3

With such symptoms, in principle, anything can happen - PSU, RAM, disk, the motherboard itself ..
I would advise you to change one element of the system and check after that.

Answer 4

What voltages does the BIOS show, what do the capacities look like on the motherboard?