more than likely it is ram, or you are overclocking and the ram timings are messed up. If you are overclocking, can you turn off your overclocking to see if that is the issue?
if you are not overclocking, I would suggest removing all but one stick of ram, and then run memtest again on just that one stick. If you get no errors, take it out, put in the other stick and test it by itself until you find the bad stick (or sticks of ram).
Once you have identified the bad sticks, try with just the good sticks and let us know if you are still getting blue screens.