Now before you tell me that the ram voltage differance is the problem i have tried the 1GB sticks at the lax 5-5-5-18 timings at 1.8V and they will pass memtest as singles and together. The 2GB sticks also pass memtest fine. However when i put them all in together memtest will fail badly, even if i up the voltage to 2.1v it still fails. Im trying to run them all at the 5-5-5-18 timings. The 1GB sticks by themselves work fine and so do the 2GB sticks, im pretty stumped any suggestions?