i have tried installing what is supposed to be compatible ddr2 but it isnt working. i have 2 512mb installed now with 2 open slots. when i put the new memorry in it didnt boot up just beeped constantly. my specs are. RAM Installed Size 1.0 GB / 4.0 GB (max) Technology DDR2 SDRAM Memory speed 533.0 MHz Memory specification compliance PC2-4200 RAM form factor DIMM 240-pin RAM features Two DDR channels RAM configuration features 2 x 512 MB Storage Controller Type Serial ATA Controller interface type Serial ATA-300

try just 1 stick of the new ram. larry

You won't get very far if you won't post System Specs or MOBO#. Dual Chanel Boards require matched sets in specific slots if less than Max. You must specify MATCHED sets if you want dual chanel to work reliably. "Matched" is not the same as ordered together. Go to www. Crucial.com to learn about RAM and your system. Search by MFG model # or MOTHERBOARD #. There is nothing to learn from someone who already agrees with you.