Dell PowerEdge 1650

Memory Technology

There are 4 72-bit (168-pin) sockets for DIMM memory modules. These modules are registered SDRAM DIMMs, the same type used in the PowerEdge 1550. The modules are configured as 72 bits wide, to provide for ECC. A memory controller in the RCC chip set performs the ECC. The system supports from 256MB (standard, two 128MB DIMMs) up to 4GB of RAM, using the following DIMM sizes:

128MB
256MB
512MB
1GB

The DIMMs must be 3.3V registered SDRAMs, rated at PC133 speed. The DIMMs need to be inserted in pairs. If four DIMMs are installed, there is an interleaving between these pairs.

This image illustrates DIMM bank 1 with two DIMMs installed. Bank 2 is empty.

Set Combining

It is important to note that in most cases, you will experience better performance by inserting four identical DIMMs rather than just two, due to "set combining". Set combining allows the system to treat four identical DIMMs as a single bank, preventing the system from having to switch between separate banks in order to retrieve data. Because there are four DIMM slots on the system board, you will still have upgrade capability even if you add 4 smaller DIMMs vs. two larger DIMMs. For these reasons, it is recommended that if more than 128MB of memory is needed, 4 equal-sized DIMMs should be used.

Examples (not a complete list) of available memory sizes for factory installation:

Total Memory DIMMs Installed

In System 128 MB 256 MB 512 MB 1 GB

256 MB       2

512 MB

      2

512 MB
      4

1 GB

      2

1 GB

      4

2 GB

      4

2 GB

      2

4 GB

      4