Chilehardware has posted two pictures of a motherboard based on P35 Express chipsets (code name Bearlake and scheduled to be released mid-2007) featuring four DIMM 240 pins slots compatible with DDR3 memory modules. If the number of pin is similar to the DDR2 (the DDR has 184 pin), the safety device isn't identical because of the lack of retro-compatibility.
We remind you that the principal modifications of DDR3 are the voltage decrease to 1.5V from 1.8V for DDR2 and 2.5V for DDR and the prefetch increase to 8n bits instead of 2n and 4n respectively for DDR and DDR2 memory. The memory cells internal organisation has been reviewed to have a two times more important transfer rate without increasing the input / output, or external memory bus frequency. Beside the power consumption improvement, this memory will bring higher bandwidth as it will be officially available from DDR3-800 to DDR3-1600. This is two times higher than DDR2 which was available from DDR2-400 to DDR2-800. Of course, like with DDR and DDR2, some chips will provide higher performances than the official specifications and we will probably see DDR3-2000 chips which correspond to PC3-16000 (16 GB /s) memory modules.
For latency, the DDR3 won't be better than the DDR2. Micron announced the following timings:
- DDR3-800 : 5-5-5 to 6-6-6
- DDR3-1066 : 6-6-6 to 8-8-8
- DDR3-1333 : 8-8-8 to 10-10-10
- DDR3-1600 : 9-9-9 to 11-11-11
Of course, this correspond to clock cycles and DDR3-1600 memory with timings of 10-10-10 won't be slower than DDR3-800 in 5-5-5 because of the two times higher frequency. An important point, thought, is that DDR3-800 chips with timings of 5-5-5 will have slightly slower access time than DDR2-800 chips in 5-5-5 as memory cells will be clocked at 100 MHz in the first case and 200 MHz in the second.
