restart PC restart randomly

[Hemant singh]

i baught this pc about 3 years back,it has i7 4790k, gigabyte motherboard GA-Z97M-D3H, Kingston HyperX KHX1866C10D3/8G, gtx 750ti and crossair 450w psu also cooler master cpu cooler that i just baught in order to fix problem

 

this pc was running fine earlier but since last 6 months i am facing random restarts whenever in stress and while playing fifa specifically .

i thaught it was a heating issue so i baught that cpu cooler and ran a stress test it shows max temp to reach 59 degree @ 4.4 ghz (stock speed) but at this speed after 10 or so minutes of stress test again i am facing random restarts and that too without any BSOD 

 

i tried under-clocking it to 3.3 ghz and now the max temp under stress reaches 45 and the pc does not restarts in stress test but while playing fifa i am still facing the issue

tries re installing windows,reinstalling fifa, cleaning up dust, re assembling the pc

but still i m facing these restarts

may b this is due to the power supply but i am afraid if i buy new and still face the issue

 

whenever i overclock my processor ie around 4.6-4.7 and ran a stress test it just restarts immediately but at 3.3 its fine unless i game on it

 

plz provide a sollution

 

[3 Lions]

Sounds like your PSU is about to die.

[Hemant singh]

psu is fine i replaced it with other one and the pc still shutdowns 

one thing i observed is that

the pc is not able to start of oc . It just goes into boot loop and shows me to go back to default setting but then also it shutdowns.

the pc just works fine when under clocked to 3ghz

have i screwed up my CPU? or motherboard?

may b. i was just a noob when i overclocked it .