One stick at a time in the same slot should sort it
And i would not do a bios update till you have got it running ok just incase it fails.
Yea didnt update Bios lol.
Im using my 2GB set. took out the 4gb set to see if i still get bsod.
if this installs fine, then the ram set i bought is faulty.
http://www.overclockers.co.uk/showproduct.php?prodid=MY-096-OC