I have a new system with a MSI 890FXA-GD70 mobo and Phenom X6 processor with G.SKILL Ripjaws Series DDR3 1600 RAM. The system does not boot when I have two RAM modules (in the first two slots), but when I put one module in, it boots. It doesn't matter which one. When I put one module in the second slot, it also does not boot. I can also sometimes get it to boot with both modules in place, but that is rare. I've already tried everything on the list of the "computer won't boot" sticky, and am wondering what I should do now. The debug code on the motherboard is usually d1. The computer is new and there were more minor problems that occurred shortly before; such as on one boot Windows didn't detect the mouse and keyboard, and at one point there was a problem detecting an external HDD.
There might be something wrong with your mobo as it seems like one of the RAM slot isn't working the way it should since you've tested with each stick individually. That, and your USB hubs might be defective which is also part of the mobo.
I've been hoping that it wasn't that. However I did some more tests and they all point to the mobo. Furthermore it appeared to be only when working with dual channels, and I found out that the mobo was still giving the ram the wrong timings and voltage. I manually set both again and saved them as a boot profile, and I also reassembled the entire computer. It seems to be working now, but that's happened before. I'll update when I try to turn it on tomorrow morning after using it today. If it works I think I'm good.
It didn't work, although I noticed that if I take one stick of RAM out, then boot, and then put that stick back in, sometimes the computer boots, although half the time it does that it will freeze inside windows and the screen will turn black. I'm assuming I'll have to replace the mobo, but I want to get a second opinion