How do I diagnose occasional failure to power up?

[odaenathus]

Hi All,

Have a white iMac (2Ghz Core Duo, 20" screen). It has started misbehaving slightly: it usually takes two or more tries to start from off, and has to have a hard restart if I've let it go to sleep on its own.

If I have made it sleep myself, by pressing the power button, it always comes back, but it refuses to do so if I let it sleep on its own.

My local reseller suggests that it may be a logic board fault: I'll have to pay £70 to diagnose this and, if that's the case, the repair is uneconomic, meaning I've also wasted £70 ...

I've run an expired version of techtools, which suggests something is up, but won't tell me unless I upgrade to AppleCare. Can any suggest any further diagnosis I can do on my own? For example, is it worth trying a full backup/restore?

Thanks in advance!

Tim.

(And yes, I'd really like a new quad core, but I'm not throwing out kit I can reasonably salvage ...)

 

[HyperX13]

My youngest son has the 20 inch imac and it has had that issue since snow leopard was put on. I just turned auto sleep off and we just make sure the computer shuts itself down at 9pm (via parental controls). I know this is not a solution you are looking for but it seems we just need to wait for Apple to address the issue.