Intel Prague: Quad-Core 1

Intel Prague: Quad-Core Review

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One of the hottest new technologies at Intel IDF was of course the new Quad Core CPUs based on the Core technology.

Just like with the Pentium D, Intel stuffed two silicon dies into one package. This approach made it possible to bring out this chip just a few months after the introduction of the Core Duo since a lot less engineering was required. If there were four cores on a single die, the whole die design would have to be redone and validated. With two dies in one package you basically have to add just a bit of glue logic to be able to run them both.

Intel is planning to ten fold today's performance within this decade. This is only possible if you have applications that are optimized to take advantage of multiple processors. As you can see in the other IDF write-ups Intel is strongly emphasizing multi-threaded programming with their developer products.

Another important advantage of having two smaller dies vs. one big die is that the defect ratio is a lot smaller. During production there are always some parts of the wafer that yield unusable cores. If a single core had a bigger area, the chance that there is a defect in the silicon would be much higher opposed to having two identical cores that are smaller.

This slide shows the different multi-core design approaches. The current Core 2 Duo architecture has a shared cache for example which requires strategies in the silicon that distribute the available cache memory as efficient as possible between both cores. With two independent dies on the chip there is no need to share the cache between four cores, which would be a lot more complex than just with two cores. This would also need a lot of extra engineering before a new product is ready.

Here's a quick sum up of what to expect with the new Quad Cores. Initially there will be an Extreme Edition Processor called QX6700. The core speed has been reduced a little bit down to 2.66 GHz (from 2.93 GHz of the X6800) to allow this processor to operate within Intel's Thermal Budget of 130 W per socket.
The frontside bus speed will remain at 1066 MHz, the 1333 parts are expected some time in 2007. As you can expect, the price of this CPU will be very high, so Intel targets them mainly at hardcore enthusiasts, gamers and overclockers. An exact price was not mentioned, but $999 is what it is expected to be.
In early 2007 a Core 2 Quad is coming out for the more mainstream users, expect this to be a lot cheaper than the Extreme Edition processor.
Of course a Quad Core Xeon processor will also be introduced, because servers are one of the applications that often require as much computing performance as possible. There will be a Xeon Quad DP (Dual Processor) and Xeon Quad MP (Multiple Processor). The dual/multiple stands for the number of sockets, so Quad DP means up to two sockets with a total of eight cores.

All new Quad Core CPUs will need a motherboard that supports them. With the Quad CPUs a new VRM (Voltage Regulator Module) specification will be introduced that requires a minor change in the motherboard design.
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