OK, I have an XPS 720 with two 1 gig memory chips.  First off when I go to the online system configuration for my service tag, it gives no usable information on the memory that was installed .  I pulled the chips and they are Corsair Dominators but there of course is no part number.  I lookup what the online system upgrade configurator recommends for my service tag and it tells me to use the Corsair TWIN2X4096-6400C5DHX but something seems wrong, so I call Corsair.  They tell me that Dell ordered the chips with no identifiable part number by design but to use CPU-Z to get the part number form the chip.  Low and behold they are not what Dell says but in fact they are CM2X1024-8500C5D chips which is what I thought  (1066 Mhz not 800 Mhz which is what dell wanted to sell me to upgrade).   I call Corsair back and they tell me that the system may not function if I add the 2 gig chips (TWIN2X4096-8500C5D) with the 1 gig chips that are in the system (TWIN2X2048-8500C5D or CM2X2048-8500C5D0 – kit part / chip part).  They think I need to go either 4 x 1 gig chips or pull the 1 gigs and put in 2 x 2 gig chips.  This is a 64 bit system running Windows 7 64bit.    OF COURSE THE MANUAL SAYS NOTHING!!!

 

Does anyone have any ideas???