HP Compaq dc7100 DT Reference Manual page 283

In any mode, the maximum operational speed is determined by the slowest DIMM in the
system. For example, if the system is populated with a DIMM that is 333 MHz and a second
DIMM that is 400 MHz, the system will run at the slower of the two speeds.
Service Reference Guide, dC7100 361288-003 F–3