BTW, Century Micro has the only unbuffered ECC modules at 3200MHz native speed (at least that was the case on the 39x0X release day). I don't know if they can be sourced outside Japan, though.

Fun story, I actually botched my order and got 2666MHz ones... but on closer inspection, it turned out the chips on the modules were actually native 3200MHz ones. With the SPD EEPROM saying they are 2666MHz. So I ended up overclocking them at their actual native speed. And I tweaked the timings to be a little shorter than what the 3200MHz modules were advertized for.