[UncleMacro]

One of your RAM sticks is double-sided and the other is single-sided. If you want to run in dual-channel mode then your sticks should match. Many motherboard chipsets can run non-matching sticks just fine but it won't run at its maximum possible speed.

What was the exact message given by the tiny lady inside your computer?

What kind of motherboard are you running? You can get the motherboard info (as well as info about everything else) with Everest. You can get the motherboard info by clicking the "+" to the left of "Motherboard" in the list on the left, then click "Motherboard" in the sublist which opens up. The "Motherboard Name" and "Company Name" tell you what kind of motherboard it is.

If you want to test your RAM you can run MemTest86.

 

[UncleMacro]

The memory controller in an Athlon 64 is in the CPU and the RAM compatibility rules vary a bit depending on which version of the CPU you have (Clawhammer, Winchester, Venice, etc.). You can find the version of CPU with CPU-Z. I think you should be able to get two completely different modules working on any Athlon 64 by putting them in the same memory channel. That will force it to run in single channel mode. Your problems could come from trying to run one single-sided and one double-sided panel in dual-channel mode. On your motherboard I'd try the single-sided stick in "DIMM_B1" (the blue slot farthest away from the CPU) and the double-sided stick in "DIMM_B2" (the black slot farthest away from the CPU). If that doesn't work then you could try other slot combinations to see if both of the memory sticks will run together. Running in single channel mode will slow down your machine somewhat. You'd be better off running a pair of matched modules in dual-channel mode although you don't really lose all that much running in single-channel mode.