ARGGGG.. Just happened again while I was on the phone to applecare!
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This time it was slightly different in that it wasn't the usual checkboard pattern, and it was just red, but it was flickering like crazy as shown in the video.
Anyway, Applecare weren't really that helpful. Soonest appointment I could get was for monday afternoon, and I'm sure i won't be able to replicate the issue for the 'geniuses'. The applecare rep seems to think that a replacement via genius bar will result in a much faster turnaround than simply reordering again from the website.
Pretty disappointed I must say. My 2008 Mac Pro has been humming along 24/7 for nearly 9 years with nary a problem, and when I actually get a new mac to replace it, the thing freaks out after 1 day!