As much as we love the P965, its 1066MHz front-side bus is ill-equipped to handle the next generation of Core 2 processors. Those new chips will ride a 1333MHz front-side bus, and in preparation for their arrival, Intel has created the P35 Express chipset, otherwise known as Bearlake. The P35 Express features native support for 1333MHz front-side bus speeds, and it's compatible with future processors built using 45nm process technology. More interestingly, it's also the first core logic chipset to offer support for DDR3 memory.
Does Intel's new P35 Express meet the lofty standards set by the legendary 440BX and the possible legend-in-the-making P965 Express? Is the transition to DDR3 one you'll want to make? Keep reading to find out.
The skinny on DDR3
DDR2 memory has been around for close to three years now. Intel first brought it to PC desktops with the 925X chipset in June of 2004. At the time, DDR2 ran at a relatively pokey 533MHz, but in the years since it's scaled all the way up to 1066MHz, though admittedly at a much slower pace than many would have liked. DDR2 effectively hit a wall at 1066MHz. You can find premium modules today that clock up to 1200MHz and beyond, but they require loads of extra voltage and carry hefty price premiums.
DDR3 was created to push clock speeds for run-of-the-mill modules beyond 1066MHz, and to do so with lower power consumption, as well. The default voltage for DDR3 is just 1.5Vdown from 1.8V in DDR2. That's not a precipitous drop, but it's rather impressive when you consider that DDR3 is expected to scale all the way up to 1600MHz. Initially, expect to see DDR3 modules running at 1066 and 1333MHz. 1.6GHz will have to wait.
Of course, there's more to DDR3 than higher clock speeds and lower operating voltages. The size of DDR3's prefetch buffer has been increased to eight bits, which is double the four bits you got with DDR2. This prefetch buffer acts like a cache for memory, allowing DDR3 to grab more data preemptively than its predecessor. (Interestingly, DDR2's 4-bit prefetch buffer was double that of DDR memory, which had a 2-bit prefetch buffer.)
Increased densities are also on the menu for DDR3. Where its predecessor was limited to chip densities of 2Gb, DDR3 chips will be available in densities as high as 8Gb. Those denser chips will allow for higher capacity memory modules. DDR2 modules topped out at 4GB, but DDR3 modules will be capable of hosting up to 16GB of memory. That should be just enough to run the next version of Windows comfortably. We hope.
Despite its numerous advantages over DDR2, DDR3 memory modules share a similar 240-pin interface. The modules are keyed differently, so you can't accidentally plug a DDR2 DIMM into a DDR3 slot or vice versa.
Latencies are also much higher for DDR3. The Corsair DDR3 modules pictured above are rated for 7-7-7-21 timings at 1066MHz, but the company's DDR2 sticks can handle 5-5-5-15 timings at the same speed. It gets worse for DDR3-1333. Corsair's CM3X1023-1333C9DHX modules are rated for latencies of 9-9-9-24. Real-world performance tends to be dictated by the balance of bandwidth and latency, so DDR3 will have to rely heavily on the former to realize any gains over DDR2much like DDR2 had to rely heavily on its higher clock speeds to overcome its latency disadvantage relative to DDR.