Yeah, that psu has GOT to go, or you risk killing that 1080Ti.
So recently my 7 years old cheapo 500W PSU died, and it brought down my GPU with it. My GPU is already out of warranty, so I've been thinking to do the oven trick to bring it back temporarily, but I'm not certain that it will work for my situation. Is it worth a try, or should I just leave it?
forums.tomshardware.com
The OP in that thread had the same psu as you do, and it killed their gpu.
You can't run a 1080Ti on a 40 Euro psu and expect it to run smoothly - or for very long...
You need to shell out ~100 Euro - blame COVID for pricing - for a new psu before picking up a 1080Ti.