Well...i have 1gb ddr3 and 2gb ddr3. I installed the 1gb ddr3 and jt worked fine. But when i added the 2gb ddr3 it didnt work, pc says 1 short beep 1 long beep which of course indicates that there's a ram problem. Now, i installed 2gb ram alone and still same gosh darn thing. 1 short beep 1 long...