PC very slow and large fps drops after moving

Hello,


I built a computer a few years ago for work (simple things, microsoft word, etc), listening to music, films and League of Legends. I think it has never worked perfectly (long boot times, high cpu usage, turning on during the night) but it was enough for what I needed to do.

2 weeks ago I moved it about 25 km from one house to another, by car. After this, the first time I played league of legends the pc turned off after about 10 minutes in game. This would have no warning, no "turning off", screen, just power directly off. It would then try to restart and turn off after a few seconds. It could power on again if it stayed off for a while, but the problem would repeat, even while doing simpler tasks (but League did make it happen faster). The first time it happened, it happened simultaneously with a TINY accidental knock on the right side of the computer with my foot. I thought it was a problem with the GPU overheating so I opened the case and took some dust out, alot of dust was trapped in the fan. A quick test showed that the problem didn't repeat but I would have some fps drops while playing (nothing too bad but noticeable).

I have now moved to a different country and sent the computer in a box via courier. It had a 4 day journey and despite my best efforts in protecting and covering it with clothes and bedclothes, upon opening the box I noticed that the case had taken some damage on the front panel. I booted it up and it seemed ok until I tried playing a game. The FPS is constanly very low and unplayable. The computer struggles even with the simplest of tasks.
Please Help.
Thanks !
I didn't find the right solution from the internet.