Dual core: Athlon 64 X2 4800+ and 4400+ (page 1: AMD's choices)

A few years ago, AMD had already mentioned their intention to release a dual core processor based on the K8 architecture introduced with the Opteron & Athlon 64. Since September 2003, and since the launch of the Athlon 64, the release of such a processor was already specifically announced. Last June 24, AMD went even further and said that the processor design was finalized and was already included in the public Roadmaps.

Recently this process speeded up as Intel decided to get into the race so as to be the first company to announce a x86 dual core processor. The Santa Clara giant was faster than AMD and announced the Pentium Extreme Edition on April 18th last (see our test here).

Three days later, and as planned for many years, AMD announced the Opteron dual core for servers and workstations and pre-announced, in answer to Intel’s announcement, the Athlon 64 X2 for desktop computers. The processors initially weren’t available for sales and tests before June, but this date was brought forward, so this gives us the opportunity to present the Athlon 64 X2 today with this test.

AMD’s choices

With a 90 nm fabrications process, the AMD Athlon 64 X2 is made of a single 199 mm² DIE with no less than 233 millions transistors (according to AMD). The Pentium dual core’s surface is 206 mm² and includes 230 millions transistors.

Like with Intel, the AMD dual core is based on a very simple principle and includes two processors in a single Socket.

However, AMD pushed the two cores’ integration further and these two are really tightly combined together, unlike the two Intel cores that are just placed alongside each other. The two AMD cores share a single integrated memory controller and can communicate directly without using the motherboard external chipset, like with Intel’s processor.

1 : CPU 0 , 2 : Cache L2 CPU 0, 3 : CPU 1, 4 : Cache L2 CPU 1
5 : System Request Interface, Crossbar Switch, Memory Controller, Hypertransport

The only downside of this choice is that, like with Intel, the available memory bandwidth doesn’t increase as compared to a single core processor. To increase this bandwidth, we would have to integrate a second memory controller and AMD would have had to set aside the advantage of its dual core architecture: its compatibility!

In fact, the Athlon 64 X2 processors have the advantage of being compatible with all existing Socket 939 motherboards. The Opteron dual cores are compatible with all Socket 940 motherboards, which support 90 nm single core processors. For both processors a simple bios update will be required!

For thermal dispersal, AMD said that dual core processors would reach, in the worst cases, 110 Watts. This means that the improvement is only slightly higher than the 104-Watts announced for the Athlon FX-55.