Kit of CMX1024-3200C2 failing in dual channel

I have an odd issue here, I have two sticks of CMX1024-3200C2 (CL2, PC-3200, 400Mhz, 2.75V paired)... I placed one in Slot 1 and the other in Slot 3 (for Dual Channel support) on an ABit NF7-S2G motherboard with latest BIOS... I get Memtest 86 errors on Test 7, and if I place the two sticks in Slot 1 and Slot 2 (Single channel) I get no Errors on two passes... If I test the sticks individually in Slot 1 or Slot 2, I get no Errors on two passes... However, if I place either stick individually in Slot 3 I get thousands of errors on Test 7.



Here is where it gets weird... I have two sticks of Elixr 512MB DDR400 and if I place them in Slot 1 & Slot 3 (Dual Channel) I get no errors on two passes...



Most of the errors with the CMX1024-3200C2 pair seem to occour after 512MBs (although I get a few at 21.xMBs)... All on Test #7...



I have set the DDR Voltages in the BIOS to 2.8V (BIOS only has increments of 0.1)... I tried everything between 2-3-3-6 to 3-3-3-8 and I still get errors on Test #7 in dual channel... Individually in Slot 1 & Slot 2 I can run them easily at 2-3-3-6 with no errors on two passes.



I'm not sure if it's dodgy RAM Modules, a dodgy Chipset, dodgy CPU, or dodgy Motherboard RAM slot... I'm pulling my hair out on this... :confused: Any ideas? Thanks.