AN8-SLI + 2x1GB DDR400...What's the problem? Disgruntled.

So here's the deal. The memory in my system was as follows: 2 x 512MB OCZ dual channel kit (OCZ4001024ELDC-K) plus a 1GB module of OCZ4001024ELPE. All three were DDR400 memory and as installed, all ran very happily at the full 400MHz DDR speed at 2-3-2-6 timings (default). The configuration was like this because I upgraded from my socket A platform this past winter.

As you can guess, it was running in dual channel in the socket A setup, but obviously in single channel in my current 939 setup. Since I wanted dual channel, because why not, I bought another module of memory this week (arrived from Newegg today) that is identical to the 1GB module I already had - OCZ4001024ELPE (for some reason it's CAS is 2.5 by SPD. Bizzare, considering the part number is identical to my other stick, which is 2.0 by default).

So I plug it in, and I notice it says single channel, DDR200. The setup looked like this:

Bank 1 2 3 4
1GB, 512MB, 1GB, 512MB.

I managed to decode the confusing motherboard manual to figure out how to get dual channel, and so I changed it around to be this:

Bank 1 2 3 4
1GB, 1GB, 512MB, 512MB.

Boot up and it says dual channel. Okay, progress. But wait, it says DDR200. I think WTH? Maybe it's some stupid problem with having all 4 ram slots full? So I take the pair of 512s out so that it is just the two 1GB modules.

Still DDR200, dual channel. Hrmm. Move 1GB from bank 4 to bank 1, so the RAM is in bank 1 and bank 3. As expected, it boots up and says single channel. Right then.

Change back to both of them in bank 3 and 4. I go into the BIOS and manually set the memory to be DDR400, because, you know, it's DDR400 ram and all. Won't boot. Ok, clear CMOS. Set back to DDR400, but change command rate to 2T. Won't boot. Right then. Clear CMOS again and leave to "by SPD" in DRAM config section.

Turn it off and remove 1GB. So now the system is operating with just a single 1GB stick. Boot up, DDR400, woot! Okay, I figure my new one is bad or something. So I put it back in, remove the one I just tested, and boot again. Woot, DDR400 it says! So I think what the hell?

I put them both back in together, and once again, it says DDR200. Um, yeah. Ok. So both of the modules operate at DDR400 when they are alone in the system. But put together, the motherboard hits them with the nerf bat down to DDR200 (so a real clock of 100MHz, confirmed via memtest and CPUZ) and won't boot if that frequency is tampered with manually.

I flashed the BIOS to the latest version on Abit's site, because it said that it fixed some memory compatibility issues. No change, I still get this exact same problem. I did some Google searching and can't find anything that might mean some sort of inherent defect in using 2 or more 1GB modules together. Further, both go through memtest ok (I know, not the end-all be-all test, but its good to know).

So, stumped. Ideas? Links to threads or sites that point to some obvious answers, solution, discussion or otherwise? I am really lost and am going to be seriously upset if my shiny new 1GB module paired with my other, identical 1GB module won't play nicely together in anything higher than DDR200. I really wouldn't care if the problem was that the CAS was stuck at 3 or some other stupid thing. But I DO care that my memory speed and bandwidth is being cut clean in half when using more than one 1GB module.

ARGH. Help!

This is an OLD post, but I will throw my 2 cents in here! I would bet you have a weak/sensitive memory controller on your particular CPU. Seeing as how that is primarily controlled by the CPU, I would blame that! Unless of course the chips on your new RAM stick are actually different type modules. For example one is TCCD and one is BH-5/CH-5 type RAM.