OCC has published a new review of the Mushkin 4GB (2 x 2GB) XP2-6400 Memory

While keeping the stock timings of 4-4-4-12 on the Mushkin 4GB XP2-6400 set of RAM, I wanted to see just how far I could push it. After trying multiple frequencies, the highest I could get the RAM was DDR2 888 (444MHz). I knew that if I loosened up the timings, I could go much higher. I loosened the timings to 5-5-5-12 and got the RAM all the way up to DDR2 1086 (543MHz) before I hit a wall. The HP2-6400 4GB set got all the way up to DDR2 1072 (536MHz) at 5-4-4-12 latencies, which is stock, so it'll be a good comparison to use against the slightly higher XP2 frequency.

Mushkin 4GB (2 x 2GB) XP2-6400 Memory Review