Arbitrary reboots of GA-D425TUD?

Question

Iron

The computer itself began to reboot on the GA-D425TUD. I turned off everything superfluous, vacuumed it, changed the PSU, changed the RAM, turn it on, go into the BIOS, the temperature of the processor is less than 40 degrees. It can normally stand for 10 minutes, it can reboot constantly, or in a minute.

Answer 1

and oz to test memtest?

Answer 2

Installed RAM from a work computer.
Configuration GA-D425TUD mother + proc. I start without hdd, I go into bios, it reboots even in bios.