Dell XPS 720 upgrade to CM2X2048-6400C5C - Blue Screens

I've got 3GB of factory RAM from Dell in my XPS 720 tower right now. I just ordered four sticks of CM2X2048-6400C5C. Even Dell indicates this memory will work and that I can have up to 8 GB of RAM in this machine.

I installed all four earlier today. BIOS shows 8GB of RAM, but shortly after I got into Windows XP and went into Computer Mgmt to see if Windows also said 8GB, I got a blue screen. I dropped back down to just two sticks and got the same issue - all after getting into Windows, so the computer boots up fine.

I have since put the old RAM (uses all 4 slots) back into the machine and it's fine. So, I don't think there is any problem with the mobo or the slots and I'm really not sure that there is an issue with the sticks either. Just wondering the best way to approach this situation so I can get the benefits of these new RAM sticks from Corsair.

Any suggestions? Thanks all.

What's the part number of the memory KITS you bought (not the individual sticks).

Note that the Dell sales pages differ from what they actually guarantee on the tech side.

Package has Corsair insert with XMS2 DDR2

4GB

2 X 2GB

DDR

Under bar code shows 10460552

TWIN2X-4096-6400C5C G

Purchased from NewEgg on this page:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820145241&nm_mc=TEMC-RMA-Approvel&cm_mmc=TEMC-RMA-Approvel-_-Content-_-text-_-

The sticks show 800MHz 2048MB 5-5-5-18 1.80V ver6.1

Try lowering the memory speed to 667 MHz.

Sorry for the ignorance, but what's the best way of doing that? When I first looked in the BIOS before, didn't see where to tweak RAM settings.

I did go into the BIOS (after downloading the latest version yesterday) and the memory settings appear to be read-only.