Overclocking Legends: The Barton 2500+
In the first post of this series I wrote about the Athlon XP 1700+, the cheap chip that could run with the flagships. The Barton 2500+ was its big brother, and it pulled off the same trick a year later. It’s also the chip that was sitting under my first water-cooling loop, so this one’s a little personal.
What it was
In 2003 AMD released the Barton core, which was the Thoroughbred B with the L2 cache doubled to 512KB. It was the last big update to the Athlon XP before the Athlon 64 took over, and it went all the way up to the 3200+.
The 2500+ was the cheap end of the Barton line. It ran at 1.83GHz, an 11x multiplier on a 166MHz front-side bus. And the 3200+ ran at 2.2GHz, an 11x multiplier on a 200MHz bus. You can probably see where this is going.
The easiest overclock ever
Put a 2500+ on a good nForce2 board, raise the bus from 166 to 200, and you had a 3200+ for about a third of the price. A lot of chips did it at stock voltage. Same core, same cache, same multiplier, same speed. The only difference was what AMD printed on the box.
That’s why the 2500+ was one of the best-selling enthusiast chips of its era, and why it pairs so well with Winbond BH-5. On a 200MHz bus, you wanted memory that could keep up at tight timings, and that was BH-5. A Barton on an Abit NF7-S with a pair of BH-5 sticks was about as good as a 2003 gaming PC got.
If you wanted more, you raised the bus further or got your hands on an unlocked chip. Early Bartons could have their multipliers changed, and later AMD locked them. Then there was the mobile Barton, the Athlon XP-M 2500+. It was built for laptops, ran at a lower voltage, and was unlocked. Put one in a desktop Socket A board, raise the voltage and the multiplier, and the good ones often went past 2.4GHz on air. It became one of the most hunted chips of the Socket A years, and it set up the idea, which came back with the Pentium M a couple of years later, that laptop chips made great overclocking chips.
My first water-cooled build
I already told this story in the site history, but it belongs here too. For my first water-cooled PC I went down to the local NAPA Auto Parts and picked up a heater core from a ’67 Chevelle, grabbed tubing from Ace Hardware, and hooked a Swiftech waterblock on a Barton 2500+ up to an Eheim 1250 aquarium pump.
That was water cooling back then. There weren’t many kits you could buy off a shelf, so people built loops out of car parts and fish tank pumps. A heater core was cheap, it was made to move a lot of heat, and if you could find one with the right fittings, it worked as well as a lot of real radiators. The Barton was a good chip to learn on, too, because it was cheap enough that killing one wasn’t the end of the world.
What we said about it
By the time InsaneTek started reviewing hardware in 2004, the Barton was already the old guard. It showed up in our reviews as the CPU everyone already had. Our CPU Scaling news post in 2004 used “an AthlonXP 2500+ or a Pentium4 2.4GHz” as the example of a slower CPU that would hold back a new graphics card in games like Far Cry. And our Zalman Reserator review remembered “when Athlon XP-Mobile chips were popular,” when the only thing that mattered was cooling, not noise.
Where it is now
The Athlon 64 came out in late 2003, and by 2005 the Barton was a budget chip. AMD kept selling Barton-based Semprons for a while after that.
But for a couple of years, the 2500+ was the answer to “what should I buy?” for anyone who wanted a fast PC without paying for it. Retro builders still look for them, and the XP-M 2500+ is still a prize. And if you ever come across a heater core from a ’67 Chevelle with tubing still clamped on, it was probably somebody’s first loop.
Next week: the Pentium 4 2.4C, Intel’s answer to the cheap overclocking chip.
— Luke