Dell 720H2C appendix DDR2 Memory Overview

	slot (SLOT4)
19	PCI-Express x16 card	20	RTC reset jumper	21	battery socket (BATTERY)
	slot (SLOT7)		(RTCRST)
22	password jumper	23	power connector	24	floppy drive (DSKT)
	(PASSWORD)		(POWER2)
25	card cage fan	26	liquid cooling	27	processor (CPU)
	connector (FAN_CAGE)		assembly
			(TEC_PUMP)

28processor fan connector (FAN1_CPU)

Memory

You can increase your computer memory by installing memory modules on the system board.

Your computer supports DDR2 memory. For additional information on the type of memory supported by your computer, see Memory.

DDR2 Memory Overview

•DDR2 memory modules should be installed in pairs of matched memory size and speed. If the DDR2 memory modules are not installed in matched pairs, the computer will continue to operate, but with a slight reduction in performance. See the label on the upper-right or upper-left corner of the module to determine the module's capacity.

NOTE: Always install DDR2 memory modules in the order indicated on the system board.

The recommended memory configurations are:

¡A pair of matched memory modules installed in DIMM connectors 1 and 2

or

¡A pair of matched memory modules installed in DIMM connectors 1 and 2 and another matched pair installed in DIMM connectors 3 and 4

NOTICE: Do not install ECC memory modules.

•If you install mixed pairs of PC2-5300 (DDR2 667-MHz) and PC2-6400 (DDR2 800-MHz) memory, the modules function at the speed of the slowest module installed.

•Be sure to install a single memory module in DIMM connector 1, the connector closest to the processor, before you install modules in any other connector.

.

A

matched pair of modules in DIMM connectors 1 and 2 (white securing clips)

B

matched pair of memory modules in DIMM connectors 3 and 4 (black securing clips)

NOTICE: If you remove your original memory modules from the computer during a memory upgrade, keep them separate from any new modules that you may have, even if you purchased the new modules from Dell. If possible, do not pair an original memory module with a new memory module. Otherwise, your computer may not start properly. You should install your original memory modules in pairs either in DIMM connectors 1 and 2 or DIMM