Question Black screen after a few minutes of playing demanding games

[Mark420]

Hello everyone, soo like one week ago I started getting black screens with the sound continuing, (so as i found out it should be a gpu problem). As an example I can run Overwatch on 200 fps in 2k and low settings. But Apex legends crashes after like 10 minutes.
I got a R9 390 series. When the crash happens the temperature is around 80 celsius. This gpu has just turned 4 years old but I never overclocked it. My cpu is a i7-4790k. Sad to say im really not good at hardware stuff so if any information is needed, please ask me what you need.
I'd really love to see any help.
Best regards, Mark

[edit] might underclocking the gpu help?

 

[RobCrezz]

Yeah try a 50mhz underclock.

 

[Mark420]

Underclocked it and same thing happened at about 80 celsius gpu temp. Just lasted a bit longer

 

[Mark420]

Alright i found out that overwatch crashes too if I put the graphics up a bit.
Is this a sign of the gpu getting weaker or the PSU or temperature?

If anyone would take time to help me through discord just go ahead and add me: Technician#4140 I'd appreciate it