Ok, I did some testing and with the two 1gig PC3200 and the two 512mb PC3200 ram sticks in, my BIOS reads this:
Memclock index value (Mhz) 333mhz
CAS# latency (TCL) 3
Min RAS# active time (Tras) 7T
RAS# to CAS# delay (Trcd) 3T
Row percharge Time (Trp) 3T
Row cycle time (Trc) 10T
Row refresh cyc time (Trfc) 11T
Read-to-Write time (Trwt) 4T
Write recovery time (Twr) 3T
1T/2T Memory Timing 2T
and with just the two 1 gig 3200 sticks in it reads this:
Memclock index value (Mhz) 400mhz
CAS# latency (TCL) 3
Min RAS# active time (Tras) 8T
RAS# to CAS# delay (Trcd) 3T
Row percharge Time (Trp) 3T
Row cycle time (Trc) 11T
Row refresh cyc time (Trfc) 13T
Read-to-Write time (Trwt) 5T
Write recovery time (Twr) 3T
1T/2T Memory Timing 2T
So i see what you mean by it dropping to 333mhz. Guess from these numbers it is best to stick with 2 gig using only 2 slots. So if Windows Vista handles the memory better then when using all 4 slots, it should be at 400mhz like it is with only 2 sticks?