If you install a single DIMM in an Intel Dual Channel Memory system, you will achieve only half the Memory performance that should be possible.

Installing matched pairs of DIMMs – in the correct sockets – will double the Memory Performance and increase the overall system performance by 10-25%, compared to systems with the single DIMM.


Background

For background information on the Intel Dual Channel Memory Architecture, please see these documents:

Intel Dual Channel DDR Memory Architecture White Paper
http://www.kingston.com/newtech/MKF_...Whitepaper.pdf

Dual Channel DDR400 memory can balance the performance of the Intel Pentium 4 processor with 800MHz front side bus.
http://www.intel.com/design/chipsets/dual_ddr_sb.pdf


Personal Experience

I bought a PC from a major manufacturer that had a single factory-fitted 256MB DIMM.

I installed a matched pair of PC3200/DDR400 DIMMs - in the correct sockets - and measured the following memory performance improvement:

Pentium 4, 3.2GHz
Single DIMM 2947 MBytes / sec
Dual DIMMs 4664 MBytes / sec
( SiSoft SANDRA benchmark )

The Intel and Kingston documents suggest that this results in a 10-25% improvement in overall system performance.

I did not learn about this possible performance improvement by reading the manufacturers literature, as this aspect was poorly documented, or by calling their Technical Support line.

I hope that this helps users understand this subject better.