Hi everyone! 
As the title says, I just upgraded my GPU, but am now running into severe performance issues. Overwatch went from a stable 144fps (custom settings, mid-high) to an average of 55 FPS. Fortnite refuses to even start a match now (I get stuck on a loading screen).
I thought it might be a driver issue so I tried uninstalling them with both DDU and the AMD cleanup tool. Nothing helped.
I noticed later that AMD Adrenalin shows that the power usage for my GPU is only around 50W in Overwatch. That can't be normal? Should I be looking at my PSU here?
I realize that my CPU (Intel Core i5-9600K) is quite older than this GPU that I just got, but the reason why I didn't upgrade the CPU also is because my motherboard doesn't support anything much newer, so it would be quite costly, especially considering I just got a new GPU. I knew that I'd be bottlenecking the new GPU but surely it can't be this bad? Everything either runs much worse or doesn't run at all.
Honestly I don't know what the issue actually is. I don't want to jump to any conclusions and spend a lot of money on upgrading my MOBO/CPU before I am sure of what the problem actually is so any advice would be greatly appreciated.
CPU: Intel Core i5-9600K
GPU: AMD Radeon RX 6950 XT
SSD: WD Black SN750
RAM: G.Skill Ripjaws V DDR4-3600 C16 DC - 32GB
MOBO: MSI Z390-A PRO
PSU: Corsair RM850x 850W 80+ Gold

As the title says, I just upgraded my GPU, but am now running into severe performance issues. Overwatch went from a stable 144fps (custom settings, mid-high) to an average of 55 FPS. Fortnite refuses to even start a match now (I get stuck on a loading screen).
I thought it might be a driver issue so I tried uninstalling them with both DDU and the AMD cleanup tool. Nothing helped.
I noticed later that AMD Adrenalin shows that the power usage for my GPU is only around 50W in Overwatch. That can't be normal? Should I be looking at my PSU here?
I realize that my CPU (Intel Core i5-9600K) is quite older than this GPU that I just got, but the reason why I didn't upgrade the CPU also is because my motherboard doesn't support anything much newer, so it would be quite costly, especially considering I just got a new GPU. I knew that I'd be bottlenecking the new GPU but surely it can't be this bad? Everything either runs much worse or doesn't run at all.
Honestly I don't know what the issue actually is. I don't want to jump to any conclusions and spend a lot of money on upgrading my MOBO/CPU before I am sure of what the problem actually is so any advice would be greatly appreciated.
CPU: Intel Core i5-9600K
GPU: AMD Radeon RX 6950 XT
SSD: WD Black SN750
RAM: G.Skill Ripjaws V DDR4-3600 C16 DC - 32GB
MOBO: MSI Z390-A PRO
PSU: Corsair RM850x 850W 80+ Gold