Question 5700xt problems

[foomdist]

I had just bought my 5700xt and a new psu. When I launch games (Rainbow Six Siege, Warzone) the screes flicker and eventually go green or black then. Everything is fine but my frames are really ------- and gpu is barley being used and the clock speeds are at 800 mhz.

Please Help

MOD EDIT: Please watch the language

 

[sizzling]

What exact psu?
What is the full pc spec?

 

[foomdist]

https://www.bestbuy.com/site/corsai...ar-power-supply-black/6356248.p?skuId=6356248