DDR3 SDRAM
From Wikipedia, the free encyclopedia
 |
This article contains information about a scheduled or expected future product. It may contain preliminary or speculative information, and may not reflect the final version of the product. |
| DRAM types |
DDR3 SDRAM (Double Data Rate 3 Synchronous Dynamic Random Access Memory) is the name of the new DDR memory standard that is being developed as the successor to DDR2 SDRAM.
The memory comes with a promise of a power consumption reduction of 40% compared to current commercial DDR2 modules, due to DDR3's 90 nm fabrication technology, allowing for lower operating currents and voltages (1.5 V, compared to DDR2's 1.8 V or DDR's 2.5 V). "Dual-gate" transistors will be used to reduce leakage of current.
DDR3's prefetch buffer width is 8 bit, whereas DDR2's is 4 bit, and DDR's is 2 bit.
Theoretically, these modules could transfer data at the effective clockrate of 800-1600MHz (for a single clock bandwidth of 400-800MHz), compared to DDR2's current range of 400-1066 MHz (200-533 MHz) or DDR's range of 200-600 MHz (100-300 MHz). To date, such bandwidth requirements have been mainly on the graphics market, where fast transfer of information between framebuffers is required.
DDR3 sticks maintain the 240-pin DIMM interface of DDR2, allowing DDR3 compatible chipsets to host DDR2 modules (though not both types at once). [1]
Prototypes were announced in early 2005, while the DDR3 specification is expected to be publicly available in mid-2007. Supposedly, Intel has preliminarily announced that they expect to be able to offer support for it in mid 2007 with a version of their upcoming Bearlake chipset. AMD's roadmap indicates their own adoption of DDR3 to come in 2008.
The GDDR3 memory, with a similar name but an entirely dissimilar technology, has been in use for several years in high-end graphic cards such as ones from NVIDIA or ATI Technologies, and as main system memory on the Xbox 360. It is sometimes incorrectly referred to as "DDR3".
Contents |
[edit] Spec standards (not finalized yet)
[edit] Chips
- DDR3-800 : DDR3-SDRAM memory chips specified to run at 100 MHz, I/O clock at 400 MHz
- DDR3-1066: DDR3-SDRAM memory chips specified to run at 133 MHz, I/O clock at 533 MHz
- DDR3-1333: DDR3-SDRAM memory chips specified to run at 166 MHz, I/O clock at 667 MHz
- DDR3-1600: DDR3-SDRAM memory chips specified to run at 200 MHz, I/O clock at 800 MHz
[edit] Sticks/Modules
- PC3-6400: DDR3-SDRAM memory stick specified to run at 400 MHz using DDR3-800 chips, 6.40 GB/s bandwidth
- PC3-8500: DDR3-SDRAM memory stick specified to run at 533 MHz using DDR3-1066 chips, 8.53 GB/s bandwidth
- PC3-10600: DDR3-SDRAM memory stick specified to run at 667 MHz using DDR3-1333 chips, 10.67 GB/s bandwidth[2]
- PC3-12800: DDR3-SDRAM memory stick specified to run at 800 MHz using DDR3-1600 chips, 12.80 GB/s bandwidth
[edit] Features
DDR3 SDRAM Components:
- Introduction of asynchronous RESET pin
- Support of system level flight time compensation
- On-DIMM Mirror friendly DRAM ballout
- Introduction of CWL (CAS Write Latency) per speed bin
- On-die IO calibration engine
- READ and WRITE calibration
DDR3 Modules:
- Fly-by command/address/control bus with On-DIMM termination
- High precision calibration resistors
[edit] Advantages compared to DDR2
- Higher bandwidth (up to 1600 MHz)
- Performance increase at low power
- Longer battery life in laptops
- Enhanced low power features and thermal design
[edit] Disadvantages compared to DDR2
- Commonly higher CAS Latency
- Lower MFIBS per Quad Cycle
[edit] References
- Raj Mahajan. Memory Design Considerations When Migrating to DDR3 Interfaces from DDR2. MemCore Inc.
