Rambus has introduced its fourth-generation registering clock driver (RCD) chip for server-grade DDR5 memory modules. The updated RCD chip brings support for higher clockspeeds on DDR5 RDIMMs, allowing for future RDIMMs to run as fast as DDR5-7200, a step ahead of their current third-generation/DDR5-6400 RCD. Faster DDR5 RDIMMs will eventually go hand-in-hand with upcoming server platforms, with AMD, Intel, and others all eyeing significantly higher memory speeds for their next round of products.

An RCD functions as a buffer between the memory controller and DRAM chips in RDIMMs, redistributing command and address signals across the module – and making up the "Registered" in "Registered DIMM". This enhances signal integrity and enables more memory devices to be connected to a single DRAM channel. To work properly. the RCD must support a specific data transfer rate, so the new RCD buffer from Rambus will enable memory vendors to build server-grade DDR5-7200 modules.

In addition to performing regular functions of RCD, the new Rambus chip also packs a serial presence detect (SPD) hub and temperature sensors, which are vital for DDR5 memory sticks on general and DDR5 datacenter memory modules in particular. Such functionality somewhat reduces costs of datacenter-grade DRAM sticks, though the costs of such devices are depend on the number of memory devices rather than by tiny chips like SPDs and temperature sensors.

RCDs are crucial for contemporary server-grade memory modules, as these devices can only reach their full memory capacity with registered DIMMs. Rambus is the first company to officially introduce DDR5 RCDs that support a 7200 MT/s data transfer rate, which will be useful for next-generation server platforms.

According to Rambus, their latest RCD chip is now shipping. Though given the long lead times in servers and server parts due to validation requirements, it's likely still some time off before it starts appearing in commercial servers and DIMMs.

Source: Rambus

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  • ballsystemlord - Wednesday, January 3, 2024 - link

    Isn't DDR5-6400 already over the JEDEC specified limits? Wouldn't server owners not go for such over-clocked speeds?
  • Eagle07 - Wednesday, January 3, 2024 - link

    Nope, the spec is listed as 4000 to 6400 with expectations to expand to 8000. The difference is it has to be stable at the 1.1v to get the jedec stamp of approval. This imc is likely to lead to the first expansion of spec.
  • ballsystemlord - Thursday, January 4, 2024 - link

    Interesting, because regular MBs currently list DDR5-6000 and above as "O.C.".
  • thestryker - Thursday, January 4, 2024 - link

    I wonder which RCD Kingston, V Color and G.Skill use as they all have 6800 RDIMMs on the market.

    None of the kits over 5600 that I've seen adhere to JEDEC standards. These seem to be aimed at the workstation market as they're coded with XMP and/or EXPO for use with Xeon W and Threadripper.
  • silencer12 - Thursday, January 4, 2024 - link

    You should contact them to find out.
  • memguy90 - Friday, January 5, 2024 - link

    The article is a bit misleading: "The new Rambus chip also packs a serial presence detect (SPD) hub and temperature sensors, which are vital for DDR5 memory sticks on general and DDR5 datacenter memory modules in particular"

    This implies that the SPD Hub and Temp Sensor functionality is integrated onto the same chip as the RCD. This is not the case. The Rambus website refers to each of these separate/discrete devices as part of the "DDR5 DIMM Chipset".

  • Harry_Wild - Thursday, January 11, 2024 - link

    Finally, Rambus is getting back up in stock price! Purchase this stock at $135 a share back in the middle 1996-97? Long time ago and went as low as $9? I did not average down but held on to it since it had good amount of cash per share. It at now $65 and went as high as $71. I just want to breakeven! LOL!

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