I currently have a motherboard,CPU,psu and thats it. My computer starts up and all the fans rev up besides the PSU fan *I dont know if its supposed to power on or not psu is Corsair TX 750 V2 thanks* and I know the computer turns off because of no ram but when I click the power button everything starts up and the cpu fan starts and then it just powers off. Could it be a problem with the fan or the PSU fan? Thanks.
I have done a bit of research and it seems that if the CPU is idle then the fan won't spin up. Best thing to do I think is too build the machine completely and see if under load the fan spins up, if it doesn't then you've got a problem, otherwise all is good. Hope this helps.