I've got a CTO MBP 15", Early 2011 with the 2.2GHz i7, 4GB of RAM and a 128GB SSD stock from Apple. To that, I added a second SSD (Crucial M4 256GB in a caddy in place of the optical drive), and everything has been running fine for a year. Since this is a heavy photography use machine and I've recently gotten the Nikon D800 (36 MP files), the 4GB of RAM has become an issue in Aperture & Photoshop. EVERYTHING I've read indicates that I've got a machine that should be having no issues with 16GB of DDR3-1333 RAM. Two weeks ago I ordered this from Amazon: -Crucial 16 GB kit (8GBx2), 204Pin SODIMM, DDR3 PC3-10500 Memory Module All the resources on the net as well as the Amazon reviews made it look like a sure fire deal. Last weekend I popped it in, verified that OS X Lion saw 16GB, and started working on photos. An hour later got a crash, which corrupted the Aperture library I was working on . An hour of research later, I grabbed the latest version of memtest, rebooted in single user x86_64 mode, and watched it fail each of the tests within ~30 secs of starting them. I threw back in the 2x2GB factory Apple modules and watching it pass with flying colors . I figured I might have gotten a bad kit and RMA'ed the RAM on Monday and ordered OWC DDR3-1333 they specifically listed under my model number. Figured it was worth paying a little more for a lower DOA rate. I installed it today and immediately gave memtest another whirl... same failures as the Crucial kit. I tested both modules separately in each slot (same results). Stock RAM is still passing all tests, so clearly I'm not having issues getting the modules seated or anything. Seems very unlikely I'd get two bad kits from two different vendors, so here I am. I searched for a couple hours on the internet for other people with similar issues and haven't found any. Anyone had problems like this? Maybe an issue with the CTO CPU/GPU upgrade and 8GB modules? (I can't see how the second SSD could cause any issues, although I'd be willing to remove it if anyone else had an experience with it fixing a similar issue.) If no one has any suggestions that can get me up and running with 16GB, I guess my next step would be to return this 16GB OWC kit and order an 8GB one. Frustrating, if that turns out being what I have to do. Help much appreciated!