Memtest fails with multiple memory modules in at one time

This is what I have in my setup:

-GIGABYTE GA-G33M-DS2R Motherboard
-CORE 2 DUO 6300 CPU
-Microsoft Windows Vista 32-Bit Home Premium OS
-EVGA 256-P2-N554-AX GeForce 7600GT 256MB 128-bit GDDR3 PCI Express x16 SLI Supported Video Card
-CORSAIR XMS2 2GB (2 x 1GB) DDR2 SDRAM 800 (PC2 6400) Dual Channel Kit Desktop Memory Model TWIN2X2048-6400 Memory

Everything has been working fine for the past year and a half or so, but over the past month or so my computer has been randomly rebooting. When it comes back on, it gives the message saying that it recovered from a bluescreen error.

I decided to run the Memtest86+ program, and it immediately came up with several errors. I then took one of the memory modules out and re-ran the test and it passed. Then I swapped memory modules and re-ran the test and it passed again. I've tried a single memory module in each of the four slots and the test will pass each time. However, if I have two memory modules in at one time then the test will get several errors. This is the case whether the memory is in dual channel mode or not.

My thought is that the problem is with the motherboard, but since the board is out of warranty, I just wanted to make sure that it couldn't be something else before I replace it. Any help would be appreciated!

Thanks.

Hey thanks for the quick reply.

I guess I should have mentioned that I added +0.1v to the voltage for the ram when I first built the computer (the motherboard is at 1.8v by default and the ram is supposed to run at 1.9v).

Am I OK to add an additional +0.1v or will that screw something up?

Thanks again.

Thanks for the input. I bumped the voltage up another +0.1, but I'm still getting errors when both modules are in. With one module in at a time, there are no errors.