what is the onboard clock speed of the RAM in the Aspire ? i notice people using 667Mhz and 533Mhz in the "official" compatability list. I'm using a Dane-Elec 533mhz becuase that's what i had availbe but am i slowing my machine down by not using 667Mhz? or is anything obove 533Mhz simply overspecced ?