Just got word that AnandTech have thrown up a new article which has extended coverage of DDR2 Performance.
DDR2 gets the majority of its punch from the 4 bit prefetch. DDR2 can effectively write/read four times the amount of data per clock cycle to/from the memory array. This effectively doubles the data bus speed while keeping the internal bus speed the same from DDR1. Both DDR1 and DDR2 use a 64-bit interface. These optimizations come with the advantage of a slightly lower operating voltage, but requires 240 pins rather than the 184 pins required by DDR today.
With the talk of different bit prefetches, it becomes difficult to tell the actual clocks of the new memory. Briefly stated, DDR2 runs with a lower internal clock than DDR1. However, since the prefetch is larger than DDR1, the external clock is doubled. For example, if we could run the same DDR400 on the shelves today with DDR2's 4-bit prefetch, it would essentially operate at DDR800. Since this is not possible, the internal bus of the DDR2 modules we see now has been lowered to 100MHz for DDR2-400 and 133MHz for DDR2-533. DDR400 and DDR2-400 should perform the same.
DDR2 Memory Performance
DDR2 gets the majority of its punch from the 4 bit prefetch. DDR2 can effectively write/read four times the amount of data per clock cycle to/from the memory array. This effectively doubles the data bus speed while keeping the internal bus speed the same from DDR1. Both DDR1 and DDR2 use a 64-bit interface. These optimizations come with the advantage of a slightly lower operating voltage, but requires 240 pins rather than the 184 pins required by DDR today.
With the talk of different bit prefetches, it becomes difficult to tell the actual clocks of the new memory. Briefly stated, DDR2 runs with a lower internal clock than DDR1. However, since the prefetch is larger than DDR1, the external clock is doubled. For example, if we could run the same DDR400 on the shelves today with DDR2's 4-bit prefetch, it would essentially operate at DDR800. Since this is not possible, the internal bus of the DDR2 modules we see now has been lowered to 100MHz for DDR2-400 and 133MHz for DDR2-533. DDR400 and DDR2-400 should perform the same.
DDR2 Memory Performance
