Faulty RAM HELP

Hi guys,

I bought 8gb corsair xms3 1600mhz 1.65voltage (2gb x 4sticks) off overclockers on the 17th jan and i was happy to see them arrive today through the post!

I originally had 8gb of kingston ram at 1333mhz which i've had to put back in.
also my board is a asus p7p55e-deluxe and it is compatible with the new ram.

i installed the new ram and it BSOD and wouldnt load windows, so i went in the bios it stated i only had 4gb of ram?? i checked the MHz and voltage and it was set at 1333mhz and voltage at 1.5 (my original ram settings) so i changed it to 1600mhz and the voltage to 1.65 but it wont load windows at all. i managed to start it in safe mode and my system states i have 8gb installed but 4gb usable??? i tried mem test 86+ but it froze...

so I have started the system with one ram stick at a time and 3 of the sticks load up ok and state there is 2gb of ram in each of the 3 but there is one stick that doesnt even go past the splash screen and also my asus board has a constant red light on the dram led with this ram stick in.

Am i right to think this is a faulty stick?

thanks