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<div>Originally Posted by <strong>TigerDirect</strong></div>
<div style="font-style:italic;">Larger Bandwidth, Better Performance<br>
DDR2 – the Overclockers’ Dream Come True<br>
DDR2 introduces features and functions that go well beyond the DDR SDRAM specification. These innovations enable DDR2 to operate at data rates of 400MNHz, 533MHz, 667MHz and more. DDR2’s enhancements stem from changes in DRAM architecture and signaling, as well as additions to the mode register for lower power and improved command/data bandwidth. Changes to the DRAM architecture include shortened page size for reduced activation power, bust lengths of four and eight for improved data bandwidth capability and the addition of eight banks in 1GBb densities and more. Without increasing your system’s clock speed, DDR SDRAM doubles the maximum data throughput of SDRAM by sending two packets of data per clock cycle, doubling its effective clock speed.<br><br>
As a result, when we refer to 400-MHz DDR SDRAM we are talking about memory that actually runs at 200MHz. SDRAM, DDR and DDR2 modules – known as Dual Inline Memory Modules (DIMMs) use 64-bit data packets. Because there are 8 bits per byte, a 400-MHz DDR module provides a total bandwidth of 3.2GH/sec. <b>Within a dual-channel 128-bit configuration, that translates to 6.4GB/sec of total available bandwidth.</b> Additionally, DDR2 adds a second port to transfer data packets to the CPU.<br><br>
Consequently, DDR2 can send two data packets per clock cycle on each of two ports for a total of four data packets per clock cycle. And this is a huge improvement over previous standards. For example, the fastest current implementation of DDR2 is a 667-MHz module, which runs at an actual clock speed of 166MHz, but offers a data transfer rate of 5.3 GB/sec in a single-channel configuration. More commonly, you’ll find a dual-channel design that features 667-MHz DDR2 modules pumping out 10.7GB sec of bandwidth.<br><br>
No Additional Strain on Your Power Supply<br>
Despite the astonishing bandwidth you’ll gain with a 667-MHz module DDR2 will not put harmful strain on your power supply. That’s because it actually consumes less power than existing DDR memory. Both DDR and DDR2 are listed by their maximum data transfer rates. Pumping out 3.2 GH/sec in a single-channel configuration, a 400-MHz DDR (known as DDR400) module is technically known as a PC3200 DIMM. Although DDR2 modules offered high latencies when they were introduced, as the technology matures this is not projected by industry experts to be a problem. When DDR2 ultimately reaches 800MHz, high-performance modules are anticipated to offer latencies of 2 clock cycles, which is exactly the same as high-performance DDR. The great news for potential overclockers is that with the same latency and twice the clock speed, 800-MHz DDR2 is expected to offer exactly twice the peak performance of 400-MHz DDR.</div>
a little old, but o well.
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