3oh6, did you try overclocking those RAM @ 1.8v? Seems to me they can run 500MHz 5-5-5-15 easily.
And did anyone notice that it says PC6400 in CPU-Z? My PC-8500 kits have the same info in CPU-Z and it's weird to me. Maybe they just pasted the markers of PC-8000 or PC-8500 onto some PC-6400 RAMs and shipped them to us.