mate I have two consoles here with the same problem, both CECHG03. In the past I've also had the same problem on other CECHG03 models. It would appear that these are the worst to fall victim of the crazy fan.
The thermal paste under the GPU has become dry and needs replacing, the problem is 95% of people will not even try and remove the IHS from the GPU. Me being one of them I have tested it on a bricked board and it was not easy and made a right mess.
I have been told the best way is to heat the IHS to 150oC and then using like a razor working from the CPU side remove each corner where it is glued down.
I hoping a mate of mine will get back in touch with me who is very experienced with the PS3 and all the reballing etc and if so I will do it under his supervision.
Maybe try and find someone who could do it for you, if you are in the USA then racer0018 might be able to help you.
OK just an update, DO NOT use a razor to remove the GPU IHS, use a blunt tool and do it from the CPU side.
Last edited by keano; 07-16-2012 at 03:36 PM.