Written by 
An update on the broken iMac, I took it to an Authorised Apple repair centre about 30 minutes drive away on Wednesday 14th Sep, dropping it off right after work. I expected them to start working in this on the Thursday and with some luck have it ready for collection by Saturday, I say this given that they had hardly any items out on the shop floor and never looked that busy. They took until Friday in fact to work out what was wrong and they come to the conclusion it was a power supply. I called them right back explaining that if you hold the power button in while plugging in the power cable, all the fans come on – this to me says it is not the power supply. They assured me thought that this is what Apple said it could be – what was I to know right?
