Introduction to DDR3

This section offers a very brief overview of DDR3 technology, however Benchmark Reviews also offers the comprehensive article: DDR3 RAM - System Memory Technology Explained. The new generation of DDR3 is meant to avoid a bottleneck between the CPU and the system memory; especially in highly overclocked scenarios. With the high-speed variety of DDR3, which presently includes everything beyond the highest 1600MHz JEDEC standard, you increase the Front Side Bus (FSB) and CPU clock speed without being forced to slow the system memory to remain stable. Here are a the primary benefits of DDR3 SDRAM:

Features:

• Now supports a system level flight time compensation
• Mirror-friendly DRAM pin out are now contained on-DIMM
• CAS Write latency are now issued to each speed bin
• Asynchronous reset function is available for the first time in SDRAM
• I/O calibration engine monitors flight time and correction levels
• Automatic data bus line read and write calibration

Improvements:

• Higher bandwidth performance increase, up to 1600 MHz per spec
• DIMM-terminated 'fly-by' command bus
• Constructed with high-precision load line calibration resistors
• Performance increase at low power input
• Enhanced low power features conserve energy
• Improved thermal design now operates DIMM cooler

Each generation of DDR is more than just an update to the memory speed, it is also a more technologically advanced production process and a lower operating voltage and better heat dissipation. The previous generation of DDR2 is manufactured on a 110nm node, whereas the new DDR3 has receives a fab process shrink down to a 90nm node (although some use 80nm) with either 55/45nm prepared for later into 2008. Together, this all helps the hardware enthusiast reach higher clock speeds at the expense of higher latencies. This is why the new DDR3 generation of memory needs a significantly higher clock speed deliver better performance than the preceding generation of DDR2 technology.

In additional to the logically progressive changes, there are also improvements made to the architectural design of the memory. One particularly important change introduced with DDR3 is in the prefetch buffer: up from DDR2's four bits to an astounding eight bits per cycle. This translates to a full 100% increase in the prefetch payload; not just a small incremental improvement as there have been in the other area's.

DDR2-400 Memory is equal in performance to DDR-400, which is why it must operate at DDR2-667 speed to carry incentive. The same scenario is generally true with DDR3 when compared to DDR2. While in theory DDR2-1066 offers the same performance as DDR3-1066, this generally means that DDR3 requires a DDR3-1333 speed to show any benefit over DDR2-800. Memories within the same generation (DDR/DDR2/DDR3) are downwards compatible, meaning that if you have DDR3-1600 RAM, you can configure it to operate at 1066 and 1333 MHz speeds.

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