1080ti running stress test on msi kombustor

[T3King]

I'm running a stress test on my evag 1080tisc that I got someday ago. I'm using msi kombustor to stress test gpu. I'm getting small stutters every so often very small tho. The picture I posted is the image on the stress test it goes up and down side to side and it stutter very little. Why is this??? Also another question. Why cant i overclock my GPU when I do it crashes right away is it that my power supplie is to low. 

How long should I run the test for????

Specs 

Mobo z370 f 

Cpu i7 8700k

Gpu evga 1080ti sc

Ram 16gb 3200 cl 14

Power sup evga 650 gq

 

 

 

[MrIceCremeLollipop]

About the OC, You might have a crappy card, But I had this issue with a old 780, I had to actually underclock it for stability But I never diagnosed it, Put it down to a bad cheap psu that was using about 470w/500 and couldnt cope, But your psu should be more than enough

[TheRandomness]

How far are you overclocking it? Are you overvolting? And the stutter could just be in that test only. Test with a game/another benchmark. Also, Furmark/Kombustor is designed to find the max power draw of the card and max heat output. Try with something like Unigine Superposition or 3DMark Time Spy.