Hello. I am soon going to upgrade my RAM from 2x 256MB (512MB Dual Channel) to 2x 512MB (1GB Dual Channel). My mother board supports up to 4 module slots. In keeping my computer's dual channel capability, I was wondering if it is alright to leave my 2x 256MB modules and just add 2X 512MB modules in the remaining 2 slots; giving me 1.5 GB of RAM. Would my computer still run on a dual channel configuration if I do this? (OPTION 1) Or is it better to simply replace the 2x 256MB modules with the 2x 512MB modules? This would make my computer run with just 1 GB of RAM. (OPTION 2) BTW, I have a Sony Vaio PCV-RS430G desktop computer. Here are its specifications: http://reviews.cnet.com/desktops/sony-vaio...13.html?tag=sub Also, it appears that my mother board's data bus speed is 800MHz. The 2x 512MB RAM modules that I am planning to buy are likely going to run at 400MHz - PC3200. Would they really run at this speed if I chose OPTION 1 (my 2x 256MB modules run at 333MHz - PC2700)? How about with OPTION 2? Thanks in advance. Hope to hear from you guys soon.

PC3200 runs at 400Mhz, but on a double pumped bus, which means effectively 800Mhz. So PC3200 is the fastest RAM your motherboard supports. Using all your RAM sticks should work, but you'll have to check the motherboard manual how they should be seated to take advantage of dual channel. However, if you use all your sticks the motherboard will most likely restrict the faster PC3200 sticks to PC2700 speeds, so that all sticks use the same speeds.