PC Graphics

[CallMeAlexich]

Hello everyone boys. I have a question: 

I7 12700f, 32 gb RAM, rx6700xt by Sapphire 12 gb. Bought a new system, but video card I took from my friend which he is used for mining ️. It's not a problem as she was working only for a year and was never more hot than 80 degrees. 

I have a problem that sometimes, during random things like playing cs:go, from time to time I can see gray stripes(screenshot

In CS:GO it happens after every alt tab and immediately disappearing, played metro Exodus - didn't had such problems, from time to time I can see same stripes in the windows hello window. 

 (approximately place where it happens), but not all the time. Furmark gpu hotspot max - 90, gpu in general 73-74. The question is: is it problem in video card my friend sold me,  or maybe it can be power unit which is only 550w for all this? Thank you for answer, hopefully I will solve my issue .

Have a good day everyone 

[CallMeAlexich]

Or maybe first it's better to change thermopaste?