Need help with 4GB RAM

Hey guy

recently I bought 2 similar RAMs each one is 2GB 800
but when I installed them I found many problems like :
- when I run anything with sound I hear strange sound instead ( like what you hear when tuning the radio )
- and when I run a game or any high graphic application it crashes

so I tried to reinstalled windows and i found the problem of sound has resolved but after I installed the graphic card driver ( catalyst 8-12) and set the resolution to 1152*864 and applied windows aero the same problem back again

I guessed that it's a psu problem so I got a 500W one instead of my 350W and tried it but the same **** problem again

Please anyone have any idea about this problem tell me what to do coz I'm running only one of them now and took off the other

and these r my specs if u wanna know :
CPU : AMD Athlon X2 5000+
MB : gigabyte ga-ma69vm-s2
video card : powercolor ati radeon hd 3650 1GB ddr2
and windows vista ultimate x64 sp1 ...........

I tried each one separately and it worked well
the problem occured when I put both of them

1) how come ? they are the same model
2) and I tried the single 2GB RAM in the hole 4 slots and it worked well