Dual Core in Detail
Dual Core started some six months ago with Intel introducing the first desktop Dual Core CPU, and AMD going the opposite road with the first Dual Core server CPU. Dual Core is simple on the Intel front; it's just the art of using two separate CPU dies and placing them into a single physical package.
The Intel parcel has the CPU dies due off from each other, meaning they do not physically connect like the AMD Athlon 64 X2, which has two dies built into one direct package. Intel's Dual Core in technical specs resembles a Dual Xeon system. There are two separate CPU's using the Front Side Bus in order to communicate, which tends to be the Intel bottleneck compared to AMD.
AMD's Dual Core uses a Hyper Transport link to connect the two CPU's together to communicate without having to go to the main bus or memory controller, which allows core to core communication for parallel synchronisation. Intel's Dual Core needs to go back to the Northbridge and send a request to the second core if the first core wishes to know what core #2 is doing - an extremely latency heavy process. None the less, two cores work better than one and Intel has its design on the table.
Currently, Intel has two versions of the Smithfield core, the Pentium D 800 series and the Pentium Extreme Edition 800 series. First let's look at the Pentium D incarnation.
Pentium D is the mainstream CPU for Intel, Pentium D is set to replace the entire Pentium 4 range. The major points for the Pentium D are its 800MHz FSB, support for EM64T, 1MB L2 cache per core (2MB total cache), SSE3 and Enhanced SpeedStep Technology. The Pentium D uses Intel's Strained Silicon at 90nm, which requires quite a bit of power to run compared to Silicon on Insulator like AMD uses. Pentium D's overall characteristics put it similar speeds clock for clock with the Pentium 4 600 series. The major advantage the Pentium D has is rather than a logical second processor, it has a physical CPU, so it doesn't have to wait for the first core to complete its task for the second core to operate. As well as this, there is a separate L2 cache for the second core, allowing it to have its own addressing while the first core is in operation, where Hyper Threading doesn't. Pentium D also features SpeedStep to place the CPU into the same reduced core states that the Pentium 4 600 series features.
The Pentium Extreme Edition 800 series uses the exact design as the Pentium D only a few extra tricks have been added to make it more attractive to the enthusiasts. Firstly SpeedStep is disabled, so no core throttling, however, the TM1 is still used for overheat protection. Second is the inclusion of Hyper Threading on each core. The Pentium Extreme Edition resembles under Windows Environments a Xeon Prescott server with two CPU's with Hyper Threading on each CPU, leaving Windows finding four separate cores. Lastly, and most importantly, the Intel Pentium Extreme Edition CPU is multiplier unlocked, that's right, overclockers will love to get their hands on these. Intel leaves the multipliers from 14x up to 60x unlocked for your overclocking pleasure similar to how AMD leaves the Athlon 64 FX opened for raising the multiplier above the factory set ratio.
Presler is the last of the line for the Intel Netburst Architecture. Presler is the first to use the latest 65nm strained silicon technology. Presler core CPU's aren't technically a Dual Core but more a Twin Core system.
Smithfield cores when produced were made together in a single package, which caused some serious issues in usable yields. If one of the cores failed testing, both units had to be scrapped. Presler cores are actually separate dies on a single package linked together.
The cores are physically about 5mm away from each other. This gives Intel a much higher yield rate. The cores are tested separately, if both cores communicate together, they are glued onto the Dual Core package and sold as a either a Pentium D 900 series CPU or the Pentium Extreme Edition 900 series CPU.
One of the major architecture changes is Intel's Virtualisation technology, formally known as the Vanderpool technology. Vanderpool allows the CPU to split off and run multiple Operating Systems at the same time on one system.
The last of the enhancements to the Presler core is an increase in the Level 2 cache. Smithfield used the same L2 cache size as the Pentium 4 500 series of 1MB per core. Presler uses the same size cache per core as the Prescott-2 M core, that's 2MB per core, in all a total of the 4MB on the Presler cores. Presler will be available in both Pentium D series of two cores without Hyper Threading and the Extreme Edition with two cores and Hyper Threading.