that right they are both running together at the mo. but i just want the 333 one to work by itself, thats when i get the problems of my system not booting.i know my motherboard is ok and the memory is ok cause it will work perfect along side my other stick @ 266mhz. i was thinking that maybe the fsb on my cpu is only 266 and it aint compatible with 333mhz memory. what do u think???