Standard DRAM Memory

[JJ]

The Memory Scanner says that my Dell Dimension 8400 can take either DDR2 PC2-5300 (DDR2-667) or PC2-6400 (DDR2-800).

The computer's Front Side bus speed is specified as 800 MHz.  So, if I install the PC2-5300 (DDR2-667), will it run slower than if I install PC2-6400 (DDR2-800)?

[lordgllynn]

What memory do you have installed now?! But, to be honest, you won't really notice a difference until you start using applications that make/need quick calculations. Example: high end games, CAD programs, and video editing software.

[JJ]

The currently installed memory is PC2-4200 (although, as noted, Dell specs bus at 800 MHz).

BTW, I got this by looking at the label on the module.  Is there some other way to determine the speed of installed memory?