The chaps over at HWUpgrade have posted a new 11 kit DDR2 memory overclocking roundup. The modules they tested are all classified as DDR2-667 (PC2-5400) and DDR2-800 (PC2-6400). Here's a bit:

The test results we received today leave plenty of room for reflection. Looking at the DDR2-667 category, only two kits out of the four tested reached and exceeded DDR2-800 (400MHz). It is highly probably that the overclocking success of the modules that exceeded DDR2-800 can be accredited to the Micron D9 chips which both the Team Group DDR2-667 and Geil DDR2-667 kits used.

Looking at PC2-6400 kits we tested, we find the results to be quite varied. Mushkin's branding system seems to have worked quite well to classify their products. Their "EP" (Extreme Performance) memory had an overclock of 30% while their "EM" (Enhanced Memory) had an overclock of 17.5%. Their High Performance memory, HP, only experienced an overclock of 12.71%. The HP kit also ended up being the lowest priced kit out of all three Mushkin kits. The GSkill modules didn't display much potential for serious overclockers either, coming in at only 450 MHz.

The OCZ kits we tested all had rather constrained increments in overclocking. It seems that the primary focus for the modules was to offer a sure guarantee of running at rated speeds and voltages while being aesthetically pleasing. In other words, they weren't really meant for venturing far past default frequencies.