Possum1080,

As long as they are the same specs for the computer it doesn't matter the name brand.

Memory

Memory

The OptiPlex™ 760 system supports up to 8 GB of memory with a 32 bit operating system. The memory speeds supported are 677 MHz and 800 MHz DDR2 memory. Both dual-channel and single-channel configurations are supported.

Like DDR, DDR2 is also SDRAM-based architecture with double data rate. But unlike DDR, DDR2 has some additional features, including 4N data prefetch, differential strobes for greater noise immunity and to improve timing margins, on-die termination (ODT) to improve signal integrity, and off-chip driver calibration (OCD) to improve system timing. DDR2 SDRAM supports Suspend-to-RAM and provides enhanced power management features (Power Down mode).

What Is DDR2 Memory?

In 2004, the computer industry moved to a next-generation memory architecture called DDR2 to allow it to continue implementing faster and higher-density main memory solutions.

The transition from DDR to DDR2 is more evolutionary than revolutionary. DDR2 architecture is the same DRAM-based technology the industry has used for years but with some enhancements:.

• Higher speeds — DDR2 provides higher memory transfer rates. Current industry specifications call for transfer rates of 400, 533, and 667 megatransfers per second (MT/s).
• Differential strobes — This improvement provides greater noise immunity, improved timing margins, and less dependence on voltage reference (Vref) circuit accuracy.
• On-die termination — ODT is probably the most well-known DDR2 feature. DDR2 provides for ODT of data, strobe, and datamask signals on the DRAM, rather than on the system board. Two termination values are provided:
  • 75
  • 150
  ODT improves signal integrity. It also reduces system component costs because system designers do not have to terminate the signal on the system board.
• Off-chip driver calibration — Perhaps the most misunderstood new feature is OCD calibration. This feature provides a method for ensuring symmetry between the rising and falling edges of the signal. The result is improved timing margins. OCD calibration can also reduce the impact of variations in vendor silicon processes on the memory interface.
• Reduced voltage rail — Like previous semiconductor processes, the voltage technology for DDR2 has been scaled down from 2.5 V to 1.8 V. This can result in a power savings, but the trade-off is reduced noise margin.

Implementation Challenges

As the old saying goes, "You can't get something for nothing." Along with increased memory performance, DDR2 has a few new design challenges:

• Routing density — In general, DDR2 routing calls for wider (lower-impedance) traces, as well as greater spacing between adjacently routed signals. This design consumes valuable space on shrinking board form factors.
• Electrical loading — As the operating speed of the memory interface continues to increase, electrical loading (the number of capacitive loads) will become a limiting factor.

Memory Configuration

DDR memory can run in dual-channel mode, which allows the system to have twice the memory bandwidth using the same memory technology.

Dual-Channel Configurations

The MT chassis has four memory connectors. To achieve dual-channel performance, the total memory in each channel must be the same. If the channels do not match or if the system has only one DIMM installed, the system memory operates in single-channel mode. The system works normally in single-channel mode, but the user loses the benefit of increased memory throughput.

Dual-channel mode is always present when both memory channels are populated. However, for dual-channel performance, the size of the modules must match.

The memory slots are keyed for DDR2 memory and cannot accept other modules. The memory modules themselves are also keyed differently. DDR RAM has 184 pins while DDR2 RAM has 240 pins. The new DDR2 memory modules physically look different than previous modules.

Use care when installing memory modules into the connectors. A greater amount of force is needed to install the DDR2 SDRAM DIMMs than on older systems.

Recommended Memory Configurations A memory module installed in connector CHA_DIMM or A pair of matched memory modules installed in connectors CHA_DIMM and CHB_DIMM NOTE: Use non-ECC memory modules only as ECC modules are not supported. Be sure to install a single memory module in CHA_DIMM, the connector closest to the processor, before installing a module in the other connector.

* Definition for interleaved is found here: http://en.wikipedia.org/wiki/Interleaved_memory

Basically, when both DIMM connectors are populated, the system has dual-channel performance unless channels A and B have different amounts of memory.

Troubleshooting

In some cases, DDR2 memory may not have the MHz listings for speed on the memory. To determine the speed, use the PCXXXX designator and divide by 8.