So, my i7 iMac arrived 11 days ago - gorgeous screen, etc. However, a couple days after it arrived, it started acting up: random beachballs, weird errors, etc, so I did a clean install and reinstalled all of my applications, and it seemed to improve, but didn't fix the problem. I did some extensive memory tests, figuring that maybe the 8GB of OWC RAM (I'm a photographer with 18-21MP images to process) that I added was causing the issue, but everything came back clean. I was just about resigned to taking it to an Apple Store (closest one is over 30 minutes away) to see if they could figure it out when I remembered the hardware diagnostics - never had to run them before, and had to hunt around before I realized they're on the applications install DVD now. Since the issues were so sporadic - the machine would run fine for hours, but then just die - I wasn't optimistic that diags would turn anything up. So, about three seconds into the first test, BAM! Memory error. So, I pulled the OWC RAM and re-ran the test - BAM! Same error. So I pulled the Apple RAM, put the OWC back in, and all tests ran fine. Put the Apple RAM back in - error came back. Pulled the 4GB of OWC RAM from my unibody MacBook and installed that, just to make sure that it wasn't the DIMM slot. Nope, everything passes fine with 12GB of OWC RAM installed, so the Apple RAM is bad - my MacBook won't even boot with it installed. Before I bought the iMac, my 1st Gen 2GHz Mac Pro suffered some sort of logic board issue - it runs, but I have to dial back the graphics card slot to 8 lanes, or I get no display output, even though the machine is actually running fine (I can screen share in just fine). All told, I'd been without a solid machine for close to a month. The iMac is now running like a dream, and I'm going to call AppleCare about the bad RAM. Will they send me replacement RAM, or will they want me to bring the iMac in to the store, etc? I REALLY don't want to have to cart the iMac in, especially if there's any chance I'd have to leave it for any length of time - I'd honestly rather spend $100 to replace the RAM myself than be without it for any length of time.