Not a boundless question just know there are a lot of tech savvy people on this forum

I have just done an upgrade on pc I have dug through a mountain of problems this time the problem I am left with is every now and then when I fire up pc is that there is a cracking audio sound I would say 1 in every 5 times I fire it up, I am running a gtx1660ti which is gen 3 on my z590 board that is gen 4, I don’t believe that is the problem my i9 prossesser specs say that the ram should run at 3200 mh I used the ram from my old system which runs at 2666 mh don’t want to send money chasing this problem I am looking towards the ram being the problem but not wanting to guess as you all know there is so much wrong information on forums most of the problems I have dealt with on this 1 no forum could help if I restart pc all is well but I would rather it be right if anyone has the knowledge would be greatly appreciated