Psu fan working before even pressing power button on front of pc

I was just wondering if I could pick your brains please?



I'm having a look at someone's desktop at the moment and when I switch the PSU on at the back of the PC the PSU fan come's on instantly along with the CPU fan and CASE fan, plus the HARDRIVE LED stay's on permenantly and the POWER and RESET button's do not change its status when pressed or held down, the PC isn't sending a signal to the monitor at all either. I've changed the PSU because I found it to be faulty after testing it and since then I've done 'process of elimination' down to a bare motherboard but the PSU fan is still coming on when switching the PSU on from the rear of the PC, so I've come to the conclusion that the motherboard is no good and I was wondering if you would be able to and wouldn't mind confirming my conclusion please???

MANY THANK'S IN ADVANCE!!!

Rob.