asus rampage 4 black edition

The motherboard or CPU seems to have failed. I've disconnected the motherboard from the case and connected 1 x 24-pin EATX Power connector(s) 1 x 8-pin ATX 12V Power connector(s) 1 x 4-pin ATX 12V Power connector(s) and start the board Results: the CPU fans not spinning unless jump started by...

My PC lags randomly for no reason. I tried almost everything. Formatting and reinstalling windows, cleaning/dusting every hardware, updating drivers, trying softwares. I don't even play games nowadays, yet it lags and stutters for 2-10 minutes. What else can I do now? :/