My Pc: i7 8700k, 8gb*2 3000mhz ram, msi rx580 gaming x 8gb graphics card, corsair 550w power supply, 144 hz monitor and the fps of CSGO is only 60-100. WHAT COULD BE THE PROBLEM
Are all your motherboard and graphics drivers up to date?
Download HWINFO and post these(or you can post a pic via imgur.com) while gaming:
cpu temps
cpu usage(each core)
gpu temps
Which Corsair 550w model? There are several: CXM, TXM, VS, CSM, RMX, and so on.
5)Download HWINFO: https://www.hwinfo.com/download/
Play the game, and take note of your cpu and gpu temperatures while in game.
6)The VS 550 is one of Corsair's junk models. It would be best to replace it, but I need you to do the other steps listed above before jumping to the psu being the cause of the low fps.