Trying to upgrade the memory in my Dell Studio XPS 8100.

I'm stumped. I'm trying to give a memory upgrade to the kid's computer. I ran the Crucial scanner and it came back that I have 4 slots, each capable of 4GB for a total of 16GB. Installed, I had two mismatched 2GB memory sticks, so I ordered a matched 8GB (2x4GB) set of PC3-12800 G.Skill memory. I did a pull and replace and the computer would not boot past the Dell splashscreen. After some Googling, it appeared that maybe 10600 was the fastest speed the computer would accommodate, so I returned the PC3-12800 and exchanged it for a set of G.Skill DDR3-1333 PC3-10600. Other than the size, this matches the specs of what is currently installed.

Same problem.

I am running Windows 7 Home Professional 64 bit edition.

If I go back to the original memory, it boots normally. At that point, if I go into the BIOS menu, I don't see anything that may help me.

I read somewhere about pulling the power plug, holding down the power button for a few seconds and then removing the CMOS battery. Then battery back in, power plug in and power up. I had hopes that would work, but it did not.

Here are the combinations I have tried:

--the two new with the two old-and switching slot pairs amongst them. RESULT: Cant get past the Dell splash screen
--the two new without the old-and switching slots between them. RESULT: Cant get past the Dell splash screen
--a single new stick. RESULT: I get a BSOD with irql_not_less_or_equal blah blah blah
--a single old stick: RESULT: Works
--the two old sticks (original configuration): RESULT: Works

Any help will be greatly appreciated.