My new Gigabyte z77 d3h motherboard with intel i5 3570 and the stock intel cpu fan. The fans (both system and cpu) run in one second spurts, then everything stops for a minute, then another spurt, and so on. As long as I give it power, it keeps jerking on and off all by itself.
I removed all connections and accessory boards except for one stick of ram, tried 3 different power supplies, cleaned and reseated the heat sink with Arctic Silver. Even tried removing the power button from the situation.
Both the case fan and the cpu fan usually sit idle, then spurt on then off repeatedly, not necessarily in unison. The cpu fan almost never runs.
I guess tomorrow I will try a new cpu fan, though (as others have said here) the fan seems to be fine. It is just illogical, Jim!