I have exactly the same motherboard & RAM chips (Corsair XMS3, 4x4GB set). After I first installed them, the computer worked perfectly fine for a month or so.
But last night my PC had shut down automatically and wouldn't boot, only did the triple-beep warning. After troubleshooting for a while, the situation is that if I put chips on the B channel, the machine will do the triple-beep-warning and won't boot.
I have the latest BIOS version installed, so I'm very confused. My PSU is a top-of-the-line Seasonic (Platinum 80 series) and I've monitored the voltages in BIOS - they seem to be all right. I don't do any overclocking or those sort of things, so I'm clueless. First it worked, now it doesn't. And there were no changes in hardware in between.
All help highly appreciated! Thanks!