What happens when i clean the cpu with tge painting wall bruch but not hard ?

Maybe you didn't put everything together right. Most components are pretty durable but I guess there is a chance static damaged something from the brush.
I'd just take everything out the components you worked on, inspect them and put it back in making sure everything is in properly and try again.
 
Well if the CPU was damaged it's unlikely ANY games would work, and if the RAM is damaged windows is likely to be unstable and crash fairly often. You should not use a brush on your PC, better to use compressed air.

You can run a memory diagnostic tool to check the RAM if you want, instructions here http://www.memtest86.com/technical.htm
If it's an intel CPU they have a diagnostic tool you can download and run to test your CPU https://downloadcenter.intel.com/download/19792/Intel-Processor-Diagnostic-Tool, I don't know if AMD have anything similar.