I remember seeing a review and tight memory timings gave a solid 5% increase in performance with Athlon64's on average. About 3%-6% increases depending on bench with A64's. Alittle less with P4's. That is almost similar increases to what the next cpu speed grade increase would give you. I run at tight timings and have not regretted it one bit. But I got a good deal on my BH5 memory. If you have the money, Athlon64 cpu's love tight timings on their memory. P4's doesn't care to aweful much, although there is a increase in every bench compared to high timings. Just my couple of penny's. I could be wrong 🙂
Jason