The release of Intel's Core i5 and i7 Lynnfield processors

The release of Intel's Core i5 and i7 Lynnfield processors and the matching P55 chipset has been followed by a new round of DDR3 memory offerings from memory manufacturers big and small. These kits all use DDR3 memory, of course, and DDR3 brings several notable improvements to the game over its predecessor DDR2. Here's a cheat sheet of what's new:

DDR3 can prefetch 8 bits per clock cycle compared to DDR2's 4 bits, A 100% improvement.

DDR3 uses less power, with 1.5 Volts nominal power supplied to chip modules compared to DDR2's 1.8 Volts. (Note that is a guideline. You will find DDR3 chip modules rated from 1.5 volts all the way up to 1.8 volts so check the manufacturer's specifications carefully).

DDR3 uses a "fly-by" topology where each chip module is connected directly to the memory controller, as opposed to the DDR2 star topology, allowing each chip module to be calibrated separately for superior performance.

DDR3's top speed (non-overclocked) is twice that of DDR2—1,600 MHz versus 800 MHz respectively—and as you'll see, DDR3 can go even faster.

You can find a detailed article on DDR3's benefits and features at Benchmark Reviews. I would like to point out an important note the article makes about the benefits of DDR3's fly-by topology:

With DDR3, the signal integrity is individually tuned to each DRAM module rather than balanced across the entire memory platform. Now both the address and control line travel a single path instead of the inefficient branch pattern T topology in DDR2. Each DDR3 DRAM module also incorporates a managed leveling circuit dedicated to calibration, and it is the function of this circuit to memorize the calibration data. The Fly-by topology removes the mechanical line balancing limitations of DDR2, and replaces it with an automatic signal time delay generated by the controller fixed at the memory system training.

The article also highlights an important new development for overclockers that comes straight from Intel. It's called XMP, which stands for eXtreme Memory Profile. Overclocking with an XMP-compatible motherboard and XMP-enhanced memory modules is a breeze, since it manages the CPU multiplier, voltages, and FSB frequencies, removing a lot of the guesswork, tweaking, and testing required when overclocking.

For the hard core techies, Chip Design magazine covered in depth many of the other improvements that make DDR3 chip modules more robust. These help provide better performance when compared to previous memory architectures, especially when it aacomes to improving signal integrity and managing impedances.