Lets try and clarify things abit: 1 = the 6700 refered to is the CPU. (Intel E6700) which is running 2 cores at 2.66 gigs <-- Has very little to do with the ram and speed 2 = 6300 IS the same as ddr2 800. 3 = Yes unless you want to use a 64 bit os you only want to put 4 gigs in your system (Note windows will only "See" 3.25-3.5 gigs of that) 4 = ddr2 runs in dual channel so you will see the best performance from matched sets. Therefore if you want to stick to 32bit (x86) you want to buy 4 1gig sticks of dd2 6300. This is the ram speed supported by your motherboard. HTH Here ---> http://ark.intel.com/products/22640/Intel-Desktop-Board-DP965LT is a spec page on your motherboard.