The AMD Athlon XP 2600+
The Thoroughbred Core Gets a Shot in the Arm...

By, Marco Chiappetta
August 21, 2002

We tested our AMD Athlon XP 2600+ using a VIA KT333 based motherboard from EPoX, the EP-8K3A+, and a 512MB stick of Corsair PC3200 DDR RAM.  After we reviewed the Athlon XP 2200+ back in June, some of our readers wondered if the Gigabyte motherboard, Taisol cooler and TwinMos memory we used to test the processor hindered its ability to truly shine.  Needless to say, we listened to their concerns, and took action.

The Test System's Major Components
First Rate Supporting Cast

     

With the Athlon XP 2600+, we wanted to appease our readers, and tested this CPU with nothing but high-end supporting hardware.  The first step we took was to replace the two TwinMos 256MB PC2700 memory modules we used last time around, with a single 512MB PC3200 DDR module from Corsair.  This particular module is capable of running at aggressive memory timings, at clock speeds well over 166MHz.  At this same clock speed, the TwinMos modules we replaced ran at 2.5-3-6-3 timings with a 2T command rate, while this Corsair module runs at 2-2-5-2 timings with a 1T command rate.

     

We also planned on replacing the Gigabyte motherboard we used in the 2200+ review.  Luckily, AMD supplied us with an EPoX EP-8K3A+ motherboard, which is a favorite amongst the enthusiast community because of its top-notch performance and its abundant overclocking tools.  The mostly aluminum Taisol cooler that shipped with the 2600+ was also replaced.  Taking its place is an all copper ThermalTake Volcano 7+, equipped with a speedy 6000RPM fan.  As you'll see later in this review, these components proved to be excellent performers, when coupled with the Athlon XP 2600+.

The Athlon XP 2600+ Exposed
The Inner Workings

We used WCPUID to get a "closer look" at our CPU.  As you can see the AMD Athlon XP 2600+ is running at an actual clock speed of 2133MHz (2138MHz in the screenshot above due to the aggressive timings of the EP-8K3A+ motherboard). This clock speed is attained by using a multiplier of 16 and a front side bus of 133MHz (16x133=2133).  Also visible above are the CacheID information, the Standard feature flags and the Enhanced feature flags. The CacheID shot shows the Athlon XP has 64K of 2-Way set associative Instruction L1 cache, 64K of 2-Way set associative data L1 cache and 256K of full speed, 16-Way set associative L2 cache.  If you add all that up, you get a grand total of 384K of effective on-die cache.  The next evolutionary step for the Athlon core is codenamed "Barton", which will increase the on-die cache to 512K.  This extra on-die cache should give the Athlons a bit of a speed boost, hopefully we'll see these processors before the end of the year.

The Athlon XP 2600+ we tested seemed to run relatively cool, considering its high clock speed.  The 2200+ we tested back in June consistently ran between 44 and 50 degrees Celsius, but the 2600+ we've got today hovered between 35 and 39 degrees Celsius.  Our methods for measuring temperature were by no means "scientific" though, and this time around we're using a much better cooler, which should account for some of the difference.  The additional 4 square millimeters of contact area probably helps a bit as well.  Regardless, the difference seemed rather substantial, so I queried our contact at AMD as to whether or not the changes made to core had a significant impact on temperature.  His response was, "I don't have a technical explanation other than our engineers have tweaked the core with all that we've discussed.  The end result was a cooler, faster CPU."

Overclocking The 2600+
Hoping For the Best

In June, when we tried to overclock the Athlon XP 2200+, we weren't exactly pleased with the results.  We were only able to bump our particular CPU up to a stable 1917MHz, a paltry 6.5% overclock.  Other sites had reported similar results, which led to widespread speculation that the "Thoroughbred" core wasn't going to scale as high as we, or AMD, would have liked.  That may have been the case with the original revision of the core, but it's not with this one!  We raised the voltage to the processor's core to 1.8v and proceeded to raise the FSB until the system was no longer stable.  Our Athlon XP 2600+ booted into Windows XP with a 155MHz FSB, or 2480MHz!  Unfortunately, at this clock speed the system wasn't completely stable, so we slowly lowered the FSB until it was.  The "sweet spot" for our particular CPU turned out to be 2413MHz (16x151MHz FSB), a full 280MHz over the default clock speed!  With a higher core voltage and some better cooling, we probably could have taken the CPU even higher.  It's looking like there is some definite headroom left in this new CPU.

    

We played Quake 3 for about 20 minutes with the CPU overclocked and were pleased to see our Athlon XP had only reached 50 degrees Celsius.  With good cooling, keeping an Athlon XP 2600+ running well within spec, even when overclocked, should not a problem.  Whether or not our overclocking results turn out to be typical for this new revision of the "Thoroughbred" core remains to be seen, but our initial results are very promising.  Hardcore overclockers will also be happy to see the L1 traces on the Athlon XP 2600+ appear to be connected from the factory.  Bridging the fifth L3 trace should be the only step needed to unlock this CPU.  We didn't attempt to unlock our CPU just yet, as soon as we do, we'll let you know.

On to the Benchmarks!