Official DDR2 specs topped out at DDR2-1066 (PC2-8500). It’s interesting to note the inverse relationship between clock rates and timings. DDR2-400 offered official timings as low as 3-3-3, but DDR2-1066 only went down to 6-6-6—a sort of two steps forward and one back affair. Many vendors marketed modules with more aggressive specs than those sanctioned by JEDEC. Vendors also started selling modules in pairs as dual-channel system architectures prevailed.