FAQ: A friend of mine recently bought a OCZ 2x1GB DDR2-1066 dual channel kit for his GA-MA78GPM-DS2H motherboard with an AMD X2 AM2 processor. He got surprised when he got home, plugged the memory in the motherboard and powered it up. How come the BIOS detects it as only DDR2-800?
According to AMD's specification sheets, the AM2 processor has a 144-bit integrated memory controller (or IMC) that operates at 400MHz (800MHz effective at double dynamic rate or DDR).
Refer to the document above for the specification (or the screenshot of its image). It explains why the BIOS detects only 800MHz memory.
Do not fret, overclocking the processor can fully utilize the 1066MHz capability of the memory without over-stressing it. That is exactly what overclockers do: Buy fast memory in order to better overclock the processor eliminating the memory as bottleneck and extend the mileage.
If not into overclocking, obtaining a modern Phenom or X3 in place of the X2 will properly detect the memory at 1066MHz. With the recent price cuts, the higher tier processors just became more within reach.
