i previously ran my pc with 2x1GB ram, installed another ram, which is a 2x2GB ram. both are corsair XMS2 with similar timings, but different volts i think.
before installing new ram, pc was fine. but know, pc won't boot, and it keeps on giving me the "Start windows normally, Last known good configuration page" and sometimes it runs, sometimes it does not. what could be the problem?
Try the 2x2GB kit by itself and see if it boots. Then if they do I'd run Memtestx86 and check if the modules are bad - I have no idea how to use it though, lol. Also, I'd try setting the memory voltage to 1.9V.
run with one stick in only, if it boots try the other one, that puts out the RAM. than update your BIOS to the latest, if that don't work. with both stick in, go back to one and try the stick in each slot you have just in case the one of the slots has gone dodgy somehow.