Mother board and memory Gigabyte GA-8KNXP Rev.1

If I place a module in A channel either of the three slots it will not boot and all I get is a constant beep out of my speakers with the power light flashing very fast like it was a hard drive running. If I place a module in B either of the three slots it will boot in single memory and run. I ran MS memory test and it said I had a bad module but cosair will not take that test they want MEM 86+ so I am running that est now but that doesn't explain why it won't boot in A channel. Any suggestions would be appreciated.

I have Tried them in each slot according to the book and then I tried one in slot 1 of A no boot. then I tried one in slot 4 of B chandle and it will boot I have placed one in slot 1 of A chanel and one in slot four both are CMX512-3200LLPT. No boot and Sound from speaker and Flashing power light. If I put one or both in Channel B It will boot and run in single mode and power light is steady. Any suggestions will be appreciated.