page_title: RDRAM
section_title: PC main memory
hierarchical_section_title: RDRAM / PC main memory
caption_attribution_description: English: A Memory RIMM Installed on Intel D850GB with Intel Pentium 4 1,5 GHz
context_page_description: Rambus DRAM, and its successors Concurrent Rambus DRAM and Direct Rambus DRAM, are types of synchronous dynamic random-access memory developed by Rambus from the 1990s through to the early-2000s. The third-generation of Rambus DRAM, DRDRAM was replaced by XDR DRAM. Rambus DRAM was developed for high-bandwidth applications, and was positioned by Rambus as replacement for various types of contemporary memories, such as SDRAM.
  DRDRAM was initially expected to become the standard in PC memory, especially after Intel agreed to license the Rambus technology for use with its future chipsets. Further, DRDRAM was expected to become a standard for graphics memory. However, RDRAM got embroiled in a standards war with an alternative technology—DDR SDRAM—and quickly lost out on grounds of price, and later, performance. By around 2003, DRDRAM was no longer supported by any personal computer.
context_section_description: The first PC motherboards with support for RDRAM debuted in late 1999, after two major delays. RDRAM was controversial during its widespread use by Intel for having high licensing fees, high cost, being a proprietary standard, and low performance advantages for the increased cost. RDRAM and DDR SDRAM were involved in a standards war. PC-800 RDRAM operated at 400 MHz and delivered 1600 MB/s of bandwidth over a 16-bit bus.  It was packaged as a 184-pin RIMM (Rambus in-line memory module) form factor, similar to a DIMM (dual in-line memory module).  Data is transferred on both the rising and falling edges of the clock signal, a technique known as DDR. To emphasize the advantages of the DDR technique, this type of RAM was marketed at speeds twice the actual clock rate, i.e. the 400 MHz Rambus standard was named PC-800.  This was significantly faster than the previous standard, PC-133 SDRAM, which operated at 133 MHz and delivered 1066 MB/s of bandwidth over a 64-bit bus using a 168-pin DIMM form factor.
  Moreover, if a mainboard has a dual- or quad-channel memory subsystem, all of the memory channels must be upgraded simultaneously. 16-bit modules provide one channel of memory, while 32-bit modules provide two channels. Therefore, a dual channel mainboard accepting 16-bit modules must have RIMMs added or removed in pairs. A dual channel mainboard accepting 32-bit modules can have single RIMMs added or removed as well. Note that some of the later 32-bit modules had 232 pins as compared to the older 184-pin 16-bit modules.
caption: A Samsung RDRAM Installed with Pentium 4 1.5 GHz
exif: {}