HP Compaq d220 MT Reference Manual page 106

Memory
Maximum operating speed is determined by a combination of the CPU and the type of memory
used. Refer to the table below for the optimum combination.
Front-Side Bus
(MHz)
400
533
800*
*Select models only.
In single channel 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 266 MHz and a second
DIMM that is 333 MHz, the system will run at the slower of the two speeds.
In dual channel mode, all DIMMs must be identically matched. DIMMs in the J23 and J24
(Channel A) sockets must be identical; DIMMs in the J25 and J28 (Channel B) sockets must also
be identical. Therefore, if you have one preinstalled DIMM in J23 and are adding a second
DIMM, it is recommended that you install an identical DIMM into the J25 socket for optimum,
dual-channel performance.
✎
If you are populating all four memory sockets in dual channel mode, you must use four identical
DIMMs for dual channel performance.
The system will automatically operate in single channel mode or a higher-performing dual
channel mode, depending on how the DIMMs are installed.
E–2
Maximum Memory Bus Speed (MHz)
PCI 2100 DIMM
266
266
266
336493-004
PCI 2700 DIMM PCI 3200 DIMM
266
333
320
Service Reference Guide, d300
266
333
400