A:AnswerMy son also had the same problem. PC would freeze then randomly restart.
We upgraded the CPU fan and it helped. He hasn’t complained recently about it anyways.
A:AnswerOn the Back side of the PC you'll see a handle like piece of metal with 2 screws, and they hold the glass and back panel on the case. Take the screws out, pull either the glass panel or back panel back and lift them to open the PC up.
A:AnswerWhile I can't say if it would fit the fan it would work with a I9-9900k or the I9-9900KS seeing how it comes with a I7-9700K inside so it would have the correct socket
A:AnswerReplacing your case is not advisable, as you would need to put your system back into the original case for warranty purposes. However, It is possible to place your components into a different case.