Bookmark and Share


Rambus, a leading developer of memory and interface technologies, this week demonstrated an XDR-based memory sub-system that ran at 7.20GHz. Rambus claims that despite of very high clock-speed, the XDR-powered system consumes 40% less power compared to GDDR5 memory sub-system.

“Future graphics and multi-core processors require significantly higher memory performance under extremely challenging power and thermal constraints. This technology demonstration highlights the outstanding power efficiency of the XDR and XDR2 memory architectures at performance levels from 3.2 to 7.2Gbps with scalability to well over 10Gbps,” said Martin Scott, senior vice president of research and technology development at Rambus.

This demonstration featured Elpida's recently-announced 7.20GHz x32 1Gb XDR DRAM device and an XIO memory controller transmitting “realistic” data patterns. Rambus has not revealed the actual bandwidth provided by the XDR-based memory sub-system, but indicated that the XIO memory controller is up to 3.5 times more power efficient than a GDDR5 controller, and the total memory system can provide is up to two times more bandwidth than GDDR5 at equivalent power.

At present, graphics cards manufacturers utilize up to 3.90GHz GDDR5 memory, which gives graphics chips 124.80GB/s of memory bandwidth in case of 256-bit memory controller. In case Rambus’ demonstration included 128-bit memory controller, the peak bandwidth would be 115.2GB/s, but in case of 256-bit memory controller the bandwidth would be whopping 230.40GB/s. It should be noted that Samsung Electronics began to produce 7.00GHz GDDR5 memory chips, which puts the industry-standard GDDR5 just a little behind proprietary XDR in terms of peak performance. 

In addition, the XIO memory controller demonstrated bi-modal operation with support for both XDR DRAM as well as next-generation XDR2 DRAM.

This silicon demonstration, shown at Denali MemCon 2009 in San Jose, is the first implementation supporting the XDR memory architecture roadmap incorporating innovations developed as part of Rambus' Terabyte Bandwidth Initiative. Implemented in the bi-modal XIO memory controller for XDR2 operation, these innovations include:

  • Fully Differential Memory Architecture (FDMA) - enhances signal integrity and increases performance through point-to-point differential signaling of clock, data, and command/address (C/A), an industry first;
  • FlexLink C/A - reduces pin count and increases scalability;
  • Enhanced FlexPhase - enables the world's highest memory signaling rates while simplifying routing and board design.

In addition, the XDR2 memory architecture includes:

  • Micro-threading of the DRAM core - introduced by Rambus in early 2005, increases data transfer efficiency and reduces power consumption;
  • 16X Data Rate - allows for extremely high data rates with the use of a relatively low-speed system clock.

Built on these innovations, an XDR2 memory system can provide memory bandwidths of over 500GB/s to a system-on-chip. A single 9.60GHz x32 XDR2 DRAM device can deliver up to 38.4GB/s of peak bandwidth, and the XDR2 architecture supports a roadmap to device bandwidths of over 50GB/s (~12.60GHz).

Unfortunately for Rambus, XDR is only produced by Elpida Memory and Samsung Electronics, and the only XDR-based device that can boast with mass availability is Sony PlayStation 3.

Tags: Rambus, XDR, XDR2, GDDR5


Comments currently: 5
Discussion started: 06/26/09 07:25:05 AM
Latest comment: 06/29/09 10:28:31 AM
Expand all threads | Collapse all threads


Yeah, this technology is nice and all, but how much is it gonna cost? How much will it inflate the price of Graphics Cards and or CPU/systems that will use it?
0 0 [Posted by: goury  | Date: 06/26/09 07:25:05 AM]
- collapse thread

A top highend graphics card with 1GB of this XDR2 mem, cannot be more than 400$, or else nobody will buy it.
0 0 [Posted by: TAViX  | Date: 06/28/09 08:38:58 AM]

Too little too late.
0 0 [Posted by: Brightstar  | Date: 06/28/09 08:38:04 AM]

I'm sure Rambus will eventually come up with a 500GHz XDR Memory Sub-System, but it still won't matter. They keep trying to push their overpriced proprietary technologies, but nobody's buying. All Rambus really wants is for everyone to start using their patented memory architectures while they sit back and collect huge royalties. It's never going to happen. At one point Rambus even tried to get in bed with Intel and even managed to secure a deal to provide a memory subsystem for one of Intel's chips. I think it was the Itanium, but don't quote me on that. Anyway, Intel wised up rather quick and dumped Rambus. Lesson here is: don't get too excited when you see a headline with the word Rambus in it.
0 0 [Posted by: Kashim  | Date: 06/28/09 08:18:08 PM]

Well, I'm posting from a system with 256MB of RDRAM. It sucks that I can build a whole new tower (with 2GB+DDR2) for the cost of 2GB(4x512) of PC800/1066 Rambus. This isn't a huge prob. 2.0P4+GF4mx needs an upgrade in a bad way too.

This company...arg...They do have some cool tech, but, have earned their reputation for a reason.
0 0 [Posted by: cheeseman  | Date: 06/29/09 10:28:31 AM]


Add your Comment

Related news

Latest News

Wednesday, November 5, 2014

10:48 pm | LG’s Unique Ultra-Wide Curved 34” Display Finally Hits the Market. LG 34UC97 Available in the U.S. and the U.K.

Wednesday, October 8, 2014

12:52 pm | Lisa Su Appointed as New CEO of Advanced Micro Devices. Rory Read Steps Down, Lisa Su Becomes New CEO of AMD

Thursday, August 28, 2014

4:22 am | AMD Has No Plans to Reconsider Recommended Prices of Radeon R9 Graphics Cards. AMD Will Not Lower Recommended Prices of Radeon R9 Graphics Solutions

Wednesday, August 27, 2014

1:09 pm | Samsung Begins to Produce 2.13GHz 64GB DDR4 Memory Modules. Samsung Uses TSV DRAMs for 64GB DDR4 RDIMMs

Tuesday, August 26, 2014

10:41 am | AMD Quietly Reveals Third Iteration of GCN Architecture with Tonga GPU. AMD Unleashes Radeon R9 285 Graphics Cards, Tonga GPU, GCN 1.2 Architecture