Need of help.... Again

[Nandit_HAF]

Pc doesn't seem to run for more than 10 minutes before stuttering and then shutting down completely . 

Cpu and gpu tests under pressure are fine . 

Didn't run memtest .

Now it doesn't even move past the ASRock screen .( After not using it for 4-5 days )

A PC service guy says the motherboard is faulty ( it's a cheap ASRock 960gc gsfx) after stating that it's heatsink is hot ( not untouchable but hot ) . I think what he's saying is fishy . He says it's 101% mbs fault . And is asking for 1/3 the price of the Mobo itself for 'servicing' it.

If it is mobo's fault then I think I should consider buying the new ryzen combo because I don't think the serviced ASRock will last long . 

The problem has been for around 2-3 weeks . 

Thanks in advance !