More core changes

By incorporating more cache within the processor core, transistor count increases from approximately 37.6 million transistors in AMD’s Thoroughbred core to 54.3 million in Barton. These additional transistors equate to a 17% increase in die size – 84mm2 in Thoroughbred versus 101mm2 in Barton. Like the Athlon XP 2800+ announced last year, maximum heat dissipation is 74.3W on the Athlon XP 3000+, while voltage remains at 1.65V. Since the Athlon XP 3000+ is running at 2.167GHz (the same clock speed as the Athlon XP 2700+), the Barton core pushes the thermal envelope a bit further than Thoroughbred clock-for-clock, but the levels are still acceptable enough for today’s latest heatsinks.

The dies compared

Thoroughbred on the left, Barton on right

Two additional Bartons

Besides the Athlon XP 3000+, AMD is launching two additional processors based on its Barton core. These are the Athlon XP 2800+ and the Athlon XP 2500+. After reading this, you’re probably wondering why AMD would release an additional Athlon XP 2800+ processor. Well, if you’ve been shopping for an Athlon XP 2800+ processor lately, you can probably guess the answer to this: supply on these processors is still limited, even though the processor was originally announced just over four months ago.

Our best guess is that AMD is still having problems getting good yields of these chips at the 2.25GHz the CPU requires and thus they’ve decided to “reintroduce” the processor with the Barton core operating at a more feasible 2.083GHz. We’ve also been told by AMD that going forward, the vast majority of Athlon XP 2800+ CPUs on the market will be based on the Barton core; therefore we wouldn’t be surprised if Thoroughbred 2800+ production is in the closing stages as we speak.

To see how the two chips stack up against each other, we ran a Thoroughbred Athlon XP 2800+ against a Barton Athlon XP 2800+. Here are the results:

400MHz bus?

While AMD demonstrated a Barton system running with a 400MHz bus speed at Comdex last year, the Barton processors announced today all share a 333MHz front-side bus. This shouldn’t be too surprising, as we still haven’t seen a motherboard capable of operating reliably at 400MHz, but we can only imagine the performance a 400MHz Barton system would bring to the table. With Athlon 64 right around the corner, these 400MHz processors will probably never leave AMD, but we’ll just have to wait and see.