Gaming PC problem help

Hi guys my friend has been having issues with his pc when he tried to play more demanding games like dayz or payday2 he would get a black screen and the sound would loop but didn't do it while playing gmod I went round his house and brought my psu and graphics card to test because and first I thought it was his psu not having enough power as it is a cheap 500w or it was a faulty Gpu but when I got round his tested the psu and had you change some boot order in the bios because it reset for some reason and I couldn't because it was alway freezing in the bios and half of the screen seem cut of but it would just freeze when I pressed setting or anything so then I thought it could be a CPU issue as I read somewhere if it freezes in bios it can be a cpu and thought it made sense more demanding games used more cpu power and that's when it crashes just wondering what your thoughts I told him to return the CPU and ram for now as its only 1-2months from Amazon.

His specs
Amd a6
R9 270x tested in my system works fine
4gb hyper x ram
Cheap msi fm2+ board can't remember which one exactly

When you are experiencing lock-ups in the BIOS, something is definitely wrong.

Initial guesses would point mostly to the motherboard, but it could have been the PSU. (Being a cheap PSU, perhaps it affected the motherboard?)

As a side-note, the A6 is not that great of a processor, especially for gaming. It is only a dual-core/single-module. It would be fine for browsing the internet, but for even entry-level gaming, you would want something with four cores/two modules. The Athlon II 860K would be a great investment.