MODULES MUST BE ORDERED AND INSTALLED IN PAIRS for Dual Channel mode. Kingston offers "K2" kit part numbers for Dual Channel mode.
Faster memory will clock down to run at optimal speed depending on processor model installed.
Depending on which processor you install, different memory modules can be utilized. Intel Xeon and some Intel Core I processors can use ECC or non-ECC UDIMMs. Other Intel Core i processors can only utilize non-ECC UDIMMs.
If 4GB is installed, the recognized memory may be reduced to 3.5GB or less (depending on system configuration and memory allocation). A 64-bit Operating System is required to utilize more than 4GB of memory.