Computer shuts down randomly - suspected PSU or memory - which one is it?

I have replaced the motherboard and CPU after the old motherboard has died. Now PC is shutting down randomly (it doesn't depend on what sort of software I am running - could be working fine with Adobe Premiere and shut down while not in use at all).

The memory sticks and PSU are still old ones from previous build.

The specs:

  • Motherboard: asus Z79-ar
  • CPU Intel Core i7
  • PSU 750W
  • 4x2gb corsair dominator-gt memory sticks

It seems to be working without shutting down with one memory stick in it. Shuts off with any two.

When it shuts down, sometimes it doesn't restart - only the fans are blowing and I need to switch it off and then on in ~30 seconds.

Heating is not the problem - checked it - all fine.

Since something has killed my previous motherboard, don't want it to happen again, but not sure which module is the faulty one - memory or PSU?


Solution 1:

The origin of the problem was in the faulty power supply, it consequently damaged first the mother board, then the RAM. After power supply was replaced, the problem was solved.