I recently had issues installing windows 7 on my brand new computer, I had to call microsoft to troubleshoot. After going through RAM tests it seems to be that one stick of my Corsair XMS3 DDR3 1600 ( 2 x 2GB ) had been deffective. He had me remove that stick completely and use the other in the first slot to boot. It worked but now I think I should return the defective RAM stick for a new one, but, I am not 100% percent sure If it is defective. I do not want to have to shut down my computer for a day or two after I just finished building it. I asked the tech support guy what would happen if i tried booting with both sticks again and he told me that it could cause errors like blue and black screens upon boot and could possibly cause Windows 7 to not work correctly. Then I asked what would happen if i try it and get errors then take it out and reboot with one stick again and he told me it's not worth taking the risk. Get this, before i had trouble with RAM i looked at system specs and it showed that i had 4GB of RAM. Whats up with that? Does that mean it's not defective? Should i take the risk or listen to Microsoft "Professionals"?