Difference Between RDRAM and SDRAM

RDRAM vs. SDRAM

SDRAM (Synchronous Dynamic Random Access Memory) is the type of memory that was prevalent in the past, and is the predecessor to the DDR SDRAM modules that we are using on our desktop computers today. RDRAM (Rambus DRAM) is another type of memory that was available as an alternative to SDRAM. The most significant difference between the two is the price. Extremely high manufacturing costs and licensing fees made the price of RDRAM modules exorbitantly high, ranging from two to three times the cost of an SDRAM module.

The high licensing costs made it difficult for other companies to use RDRAM. During its brief stint on desktop computers, it was exclusively available on Intel systems only. A contributing factor to the high manufacturing cost, is the way the memory modules were built. Each RDRAM memory chip contains an integrated memory controller. This is very different from SDRAM memory modules, where a single memory controller is located on the northbridge chip of the motherboard.

Despite its extremely high price, benchmarks showed that RDRAM modules are only marginally superior to SDRAM modules. This was done with tests that simulate the tasks done by desktop users on a regular basis. The performance gain is more significant on workstations where the tasks are quite different.

RDRAM had some quirks that you will not find on SDRAM modules. RDRAM modules need to be used in pairs, unlike SDRAM modules that can be used individually. A workaround that lets users use a single RDRAM module, is by placing it together with a CRIMM. This is the board of an RDRAM module without the memory chips. It simply allows the RDRAM to terminate properly, and work as expected. RDRAM modules also ran with a lot more heat compared to SDRAM modules. To alleviate the heating problem, RDRAM modules consistently came with heat sinks that made it heavy and bulky.

Summary:

1. RDRAM is much more expensive compared to contemporary SDRAM memory modules.

2. RDRAM was exclusively seen on Intel computers, during its brief existence on desktop computers, while SDRAM is used by all.

3. RDRAM has memory controllers embedded on each memory chip, while SDRAM uses a single memory controller located on the northbridge of the motherboard.

4. RDRAM produces marginal gains in the performance of daily tasks when compared to SDRAM.

5. RDRAM modules can only be used in pairs, while SDRAM modules can be used individually.

6. RDRAM modules run with more heat compared to SDRAM modules.

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