DFI Lanparty UT NF4-D won't post with new RAM

Alright, so I haven't upgraded my computer in 5 years, first due to lack of need, followed by lack of money, followed by apathy when I stopped gaming.

Of late, though, I've started to feel its age, especially since I picked up TF2.

As a starving college student, I can't afford to upgrade right now, so I bought a 2nd gig of ram and a replacement hip for my rig.

But I've got a problem. The OCZ Platinum DDR 3200 kit (2x512mb) I've had since I built it works fine (although I hope I haven't been running in single channel mode this entire time :\). But when I put in the Corsair "ValueSelect" dirt chip I bought, the system won't post.

If I install ONLY the new DIMM, or the new DIMM with one of the OCZ DIMMs, everything works fine. And the OCZ works fine together, as always.
No matter what arrangement I use, though, if all 3 dimms are installed in the slots, the computer will not post.

I have no ideas here. Please help!

Is it OC'ed?

Did you try increasing the vDIMM?

Regardless of all that, though, I'm not sure I'd run it in single channel mode even though you're increasing the total RAM. Another 2x512 kit would have been a better option but I understand being poor, too.

If you are running Windows XP I doubt if you will see improvement by adding the extra dimm as it would necessarily take you out of dual channel mode and 1 gig of ram for XP is plenty anyway unless you are running a very memory intensive app like photoshop. The IMC may be degraded after 5 years of use and may no longer be able to carry three dimms. Might try not only give the vdimm a boost but the vcore a boost as well to juice the IMC a little more.

From DFI FAQ before their website was redesigned about a year ago.

The integrated memory controller in AMD's 64-bit Socket 939
series CPU supports dual channel however the controller is not
capable of accurately distinguishing between dual and single
channels resulting to boot up problem. If you have luckily
booted the system, the total memory size detected is from 2
DIMMs only, not 3. Therefore we do not suggest using 3
DIMMs. From DFI FAQ about 939 Dual Channel Cpus and boards...