gpu is very unhappy

[emptycloud]

i made  a new pc and after getting everything like windows and a couple games to test it on and benchmarking tools i started with a benchmark. everything went fine it didnt like my drives but they work just fine whatever idk. when trying a game however my gpu pick the im ganna be a pain in the ass route and starts at 180 ish fps at 4k then tanks to 40-60 and stutters. i though it might be the resolution, so i changed it and same thing. after that i tried my old 1920 x 1080 monitor ,and ended with the same result. after running in a game for a bit is says it ran out of vram then after a few more trys it blues screens and restarts b4 i can read the error. my specs r i9 14900k, gigabyte 4080 windforce 16gig vers.546.33 driver , Z790 aorus master x vers. f5 bios, 2 sticks of 32 gig 6800 mt g skill ram, and a 850wat power supply. ik should have gone with a 1000w and there r some other changes that might be better for gaming. i havnt had a problem with power and i dont have a problem with overheating. i only now decided to come here bc no one else has any ideas and im clueless. 

[emptycloud]

ive run a diagnostic test on the cpu it seems fine. i changed gpus and it does the same thing on the same and lower settings