No real technical reason, Rick H. It's usually dictated by price or what's available where you're willing to shop. Alot has happened in the last six months. New sets of memory have become available and prices have dropped like a rock. I picked this set up on sale in January for $160, whereas normal price was $199. Now it sells for $129 on newegg!!! Other 2x4GB sets of 2133 memory were $200 to $220 at the time, so I figured I would get this and try to clock it up to 2133.The reason for clocking it down would be because clocking it up was unsuccessful or perhaps the need/want for tighter timings.

Corey, like Rick H, I don't understand most of this either. Would FSX get much benifit from tighter timing etc or is mostly just a let's see what I can get?.ThanksRick S.

I don't believe anybody knows for sure which is better. Dazz did a bunch of testing that showed higher bandwidth (2133 CL9 for example) provides slightly better FPS. However we all know that stutters are what really matter. Stephen has said that tight timings reduced stutters for him. It's definitely a try both and see which you prefer. I sure would love to nail this, but it would require some way of being able to record/benchmark for stutters. As it is, even FPS benchmarking using FRAPS has been brought under question by Nick, so I'm not sure of how best to benchmark FSX other than try it for yourself and see what feels best.