GPU "drops" - fps, usage, power

[Zdenda]

Hello there,

 

Ive got a new pc since summer, and i have quite problems with gpu usages and drops, as u can see in the pictures. During playing wht gpu out of nowhere reduce its power, memory and "activity" to almost 0 which result in huuge fps drop for like 1 sec, what is kinda uncomfortable during singleplay game, but problem during csgo or LoL   Temperatures are quite ok imo, around 75 C on GPU and around 70C on cpu

My current setup:
Ryzen 7 3700x,
asrock steel legend B450 (ATX),
nitro+ vega 64,
HyperX 16GB KIT 3200MHz,
WD Blue SN500 NVMe SSD 500GB,
HD WD blue 4 tb,
PSU: Corsair RM750x

Ive tried change the gpu for my old RX 580 - had the same problem BUT the fps drops vere bigger. (vega went from 120 to 30, while rx 580 went from 70 to 10) - which makes me think maybe the gpu is not the problem, but what else? powersupply? My very old Radeon HD 7790 did not had this problem, ive tried it put in the new system and for like week playing csgo/lol and no single fps drop (if we keep in mind i was around 70 fps).


My current vega 64 should be still in warranty, but... (cant really test the components in another pc, sooo  )

Thanks guys :3