I just upgraded my friends' PC with my old hardware, but it won't POST. After pressing the power button the fans turn off for around a second before shutting off. The fans turn back on for a second by themselves after a couple of seconds and it keeps doing this until I pull off the power cable. His old setup works fine, and the new one worked without issues for years on my PC. The monitor gets no signal at any point.
The monitor and everything in the build has been tested before and they work. I've tried replugging all the cables, no help there either.
The computer had an i5 2500, 16GB of RAM, a GTX 970 and a 600W corsair 80+ gold power supply. I gave him my old i7 4770 and a b85 motherboard.
It can't be due to a lack of power because I've run that i7 for years with only a 450W PSU.