hi have a problem with computer

mcdermott.clare

Commendable
Apr 28, 2018
8
0
1,510
specs are
MSI a68hm-e33-v2 memory max 32
Athlon amd x4 845processor 4x3.8ghz turbo 4x3.5hz base
8gb ddr3 Hynix
Graphics Evga Geforce GTX750Ti 2GB GDDR5 S.C superclocked GPU boost
antec 850psu changed to corsair 650vs just today
hard drive 500gb

when playing a game or watch tv or if doing two things at same time, on dual screens. and sometimes shuts down and restarts on its own, the screens turn off and i have to maually restart i replaced psu and i put graphics card into another computer and it worked fine i very puzzed to what would be the problem.
 
ive tested the memory as well no problems the case is small its Nero Black MATX Case with Front 12cm Blue LED Fan i might have a look at cpu and put new paste on it the case only has two fans