I just tried Corsair 8x2 (16gb) The machine would not boot. I tested each SIMM individually, and they both work one at a time. Interestingly, I also tried an 8 and the original 4gb, and that works! So at least it will take 12gb, which is probably all I really need. Would be most interested if anyone actually gets 16gb working, please post here with results and how you did it. I used Corsair Vengeance 16GB (2x8GB) DDR3 1600 MHz (PC3 12800) Laptop Memory (CMSX16GX3M2A1600C10) which I have read, is fairly forgiving in many situations (like 2011 MacBook Pros for example). But only one stick works for me thus far; and I don't see any configuratoin in the BIOS to help with timing issues, etc. Just refuses to boot with any display, anything.