When upgrading the system memory in a Dell Optiplex GX270 desktop from 1GB 2x512MB DDR2 PC-3200 to 2GB 2x1GB DDR2 PC-4300, I receive an error right where the Windows XP loading screen should be indicating that I should contact my support person and tell them to "load missing HAL DLLS". Returning the original memory dimms back to the machine frees me of this message and the system continues to work just fine.
The only thing that I can muster on this is that the difference in bus speed on the ram factored into the calculation of CPU speed (FSB x Multiplier = CPU Speed) somehow making Windows XP think I change CPUs?
This is a production machine that is in need of 2GB of memory. I currently only have PC-4300 memory in stock and cannot test a slower speed against my theory.