It crashed. lol. I had a kernel panic using the 2x 4GB memory sticks from my 17" MacBook Pro. At first, the system was very responsive and strong. Once I started reaching the 4GB mark, the system suddenly crashed with no warning. I've attempted this 4 times and all concluded with the same result. Here's a few photos. I apologize for the extremely horrible quality. I took it at 1/1600 shutter speed in very minimal light thinking I had the camera on Auto. I didn't notice until I imported the pictures into the system. Some notes: When the 17" UMBP was introduced with the capability of having 8GB ram, people asked if it was possible to use a MBP's copy of OSX (thinking its a possible software issue causing the limitation). The copy of OSX installed here was from my 17". I installed OSX via the 17" UMBP then removed and installed the hard drive into the 13" UMB. It booted up with no problems and it was completely stable.