Crucial 8gb ram upgrade POST error?

I have the Macbook a1342 running Mountain Lion 10.8.2, recently purchased Crucial 2x4GB RAM upgrade (Exact product: http://www.amazon.com/Crucial-PC3-12800-...)

After installing, I received the "No Ram" error code during the power-on self-test (POST): Black screen, single beep.

I did some quick troubleshooting, put in the old ram to ensure it was still functional: it was.

Ended up putting in one of the original 1gb modules, plus one of the 4gb modules, and it booted just fine, and recognizes the ram as well. I did this with both sticks, and they both booted just fine. So the memory works, it is recognized by my computer on my OSX side, as well as my windows 7 boot camp partition. Running 5gb of ram as we speak. Issue is when I try to boot it with both of the 4gb sticks.

Not sure if its because the ram is PC3-12800, or if it's DDR3L. If that's the case, I feel stupid, but the fact that it is being recognized leaves me baffled.