Intel iMac Power / Overheat issue?

Hi there,

I have an Intel iMac from 2006. About 2 years ago it started to just turn itself off randomly as if there was a power failure. When it does, the only way to power it back up is to switch it off at the plug, switch it back on and press the power button (strangely) twice. I have noticed it seems to be temperature related - when my iMac reaches around 78C (which I'm pretty sure it should be able to handle fine?) it tends to be in the danger zone and at any minute can switch itself off.

I've got around this by using smcFan Control - which thankfully displays the temperature in the menu bar meaning when I hit around 72C I can whack the fans up to full blast to keep the temperature down. Being a sound studio computer - the hum of the fans really isn't ideal, but it at least makes my computer usable. However, I'm currently in the middle of a big project on Logic and I've had to turn my room into a fridge (window open-more clothes on) to be able to work on it as all the processing involved heats it up to 75C+ in no time.

I was hoping someone could shed some light on this or at least tell me if I am right in thinking that 78C is nothing really and the iMac should deal with it easily.

I have seen tons of posts regarding the G5 iMac power problems and similar problems with the intel iMacs - I've done all the hardware resets (PRAM, SMC, PMU) as suggested in these forums but nothing has helped.

I have had the power supply changed in the past (before this problem arose) as one day it just went kaput. Don't know if that makes any difference but I'm pretty sure that the problem started a little while after the replacement was installed.

Thanks in advance!

Message was edited by: Lee_Head