I have an i7 and also took it to the Apple store rather then return it. They tested it and couldn't find anything wrong; however, ordered a new screen and cable. ( I really don't think they found anything wrong with the ones in the machine; however, thought replacing those parts might fix the issue.)
When I called them prior to the Christmas holiday, to see what was happening, they said the parts were going to take awhile to get there and perhaps I would like to pick it up, after they installed the 'firmware' fix that had just come out. (It was the day it came out.)
I decided that would be a good deal, to see if the firmware fix worked over the Holidays; as I knew nothing much would be happening at the store.
So, I brought it home and didn't see any flickering or blackouts for awhile; however, they have started once again! So, the fix didn't work on this machine.
Today, I ordered the three year iMac Applecare package and placed a call to the Apple support technician, I had worked with prior to taking it into the local Apple store.
He hasn't returned my call yet. I don't really want to send the machine back and risk getting one with the same problems or some other problem, that people are having with this model computer.
I do; however, want to make it very clear that I am still having the 'flickering/blackout' problems and I want it fixed!
I dread having to take it back to the local Apple store, as they are in a Mall with no close parking to the store, which is in the interior of the Mall. Maybe with the Applecare package I can demand that they come to my place when they get a known fix for this 'flickering/blackout' problem.
I don't really think Apple has got a fix for the problem at this time. Which is another reason I'll hold on to this one until they do.