2011 iMac - Weird and random screen pixelation

Okay so I've had my iMac about a week and have recently upgraded the ram to 16GB from Crucial.

There's not one specific thing that triggers the problem off but I know it can be easily (temporarily) fixed.

Here are some pictures of the problem





Quick fix is a reboot or to change the resolution then to change it back.

Any ideas? If the problem persists I will be booking it into the store

Thanks

Remove the memory you added and revert back to the original 2 x 2 GB modules in the upper slots. See if the graphic weirdness returns. I seriously doubt adding memory could cause those symptoms but it's best to eliminate that possibility first.

If the same symptoms show up, by all means make an appointment with your local genius bar and have the machine checked out. I know a 27" iMac is not easy to haul around but since it's under warranty, you have no other choice but to take it on in.

Looks like the GPU is 'crashing' - regularly. Head to the store, definitely.

Currently running on the original 2 x 2GB RAM, will continue for a few days to see if the problem persits

I'd say it is either graphics processor problem, a bad panel, or a loose graphics cable. Whatever it is, bring it back to the store (if nearby), or call Apple.