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Looking ahead to Intel's 925XE chipset and FSB1066

DDR2-667 Is Coming!

You can read about the basics of DDR2 memory here . DDR2 is the successor to conventional double data rate SDRAM, but does not introduce any really new technology. Data is transmitted both at the rising and the falling clock edge, which results in a doubling of bandwidth. DDR2-533 works at a basic clock of 266 MHz. Multiplying by its bus width of 64 bits will give you the bandwidth in Megabits per second. Dividing by 8 will result in MegaBytes per second. The following table includes all common DDR memory types:

MemoryClockTypeBandwidthSingle Ch.BandwidthDual Ch.
DDR266133 MHz DDRPC21002,100 MB/s4,200 MB/s
DDR333166 MHz DDRPC27002,700 MB/s5,400 MB/s
DDR400200 MHz DDRPC32003,200 MB/s6,400 MB/s
DDR2-400200 MHz DDRPC2-32003,200 MB/s6,400 MB/s
DDR2-533266 MHz DDRPC2-43004,266 MB/s8,533 MB/s
DDR2-667333 MHz DDRPC2-53005,333 MB/s10,666 MB/s
DDR2-800400 MHz DDRPC2-64006,400 MB/s12,800 MB/s

The credo of DDR2 memory is to increase the clock speed in order to get more bandwidth - even with reduced timings. CL4-4-4-12 are typical timings for DDR2-533, while the JEDEC only specifies CL5-5-5-15 for the higher speed grades. All three DDR2 memory types we received by now are able to run DDR2-700 (350 MHz) at CL4-4-4-12. Crucial does even allow for CL4-4-4-10.