iMac white and grey screen help!

[Ca2ske]

I was on my iMac "27 i7 today and twice the screen turned a dark grey colour, once in windows (bootcamp) and once in OSX. When I put the iMac to sleep by pressing the power button my desktop re-appears as normal before going to sleep.

The same issue has also happened but with a white screen.

Upon awaking my iMac it runs perfectly for a couple of minutes then the same happens.

Anyone know what the problem might be?

 

[Lord Xeb]

I was on my iMac "27 i7 today and twice the screen turned a dark grey colour, once in windows (bootcamp) and once in OSX. When I put the iMac to sleep by pressing the power button my desktop re-appears as normal before going to sleep.

The same issue has also happened but with a white screen.

Upon awaking my iMac it runs perfectly for a couple of minutes then the same happens.

Anyone know what the problem might be?

That is a tough one and can be any number of things. I personally would just take it to a repair center (not apple but one of their best rated AASPs in your area) and have them figure it out. I have seen this issue before and it has been a logic board, another time it was a hard drive. :/