When we published our 333MHz Athlon XP 2600+ review we were quite impressed with its performance, especially in relation to its predecessor. Despite running 50MHz slower than its 266MHz sibling (which operates at 2.13GHz), the 333MHz Athlon XP 2600+ finished roughly five percentage points faster than the 266MHz chip. This narrowed the gap between the 2600+ family and Athlon XP 2700+ considerably, the 333MHz CPU offered 97% of the performance of the Athlon XP 2700+ yet it officially costs 15% less. That made the chip a pretty good value in our eyes.
However, one topic we weren’t able to touch on in the original review was overclocking. During the overclocking phase of testing our reference motherboard died a premature death due to what appears to be a corrupt BIOS. With Comdex less than 36 hours away, we were left with no choice but to go with the numbers that we had. As impressive as they were, we still felt compelled to overclock our 333MHz Athlon XP 2600+ processor. Overclocking gives us an indication of how well the Thoroughbred B core the chip utilizes is scaling. Our 333MHz chip came off the line at AMD’s facility in Dresden, Germany just over two months after the initial Thoroughbred B CPUs we’d tested over the summer. We were curious to see if the newer chip may have had a few extra MHz lying under the hood. Plus, lets face it, overclocking is fun! With all that in mind, we hastily setup a new test system.
For cooling, we chose our copper heatsink manufactured by Vantec. This bad boy does a great job of keeping our Athlon XP CPUs cool, but at the expense of our ears. Every time we crank our system up with the Vantec cooler we feel like we’re on the flight line at Nellis Air Force Base, home of the United States Air Force Thunderbirds (among other things). This cooler is seriously that loud! As a result, we only crank it out when it’s time to overclock our CPUs, and even then we’ll sometimes stick with AMD’s reference coolers.
We paired our Athlon XP 2600+ system up with Gigabyte’s KT400-based GA-7VAXP and a GeForce4 Ti 4600 for video. We’d wanted to use ATI’s RADEON 9700 PRO but until VIA addresses the sluggish OpenGL performance with the KT400/RADEON 9700 PRO combination at low resolutions (where testing CPU performance is most important) we’re sticking with the Ti 4600. VIA is hard at work on a 4-in-1 driver to address this issue, which will hopefully see the light of day sometime soon.
Based on our previous experience with Thoroughbred B chips, we decided to go ahead and crank the bus up to 175MHz immediately. We wanted to know just what our chip was capable of and didn’t feel 175MHz would be too much of a challenge for our processor. Our hunch proved correct, although we did have to crank the voltage up slightly to achieve complete stability.
We slowly marched on in 2MHz increments until we settled for a bus speed of 181MHz. With the chips’ 12.5x multiplier, this resulted in a final clock speed of 2.26GHz, just a bit shy of the 2.3GHz we’d hit with our 266MHz Athlon XP 2600+ and XP 2400+, but roughly the same speed as our Athlon XP 2700+. We needed 1.8V of juice to keep the processor stable in our entire suite of tests. We were actually able to run the chip at speeds in excess of 2.3GHz in many games, but to complete all our testing we had to settle for 181MHz.