Introduction & Test Methods
When Intel released the first batch of Pentium 4 processors based on their Prescott core, which were built using a .09 micron manufacturing process, analysts found that the CPUs generated more heat and consumed more power than similarly clocked Pentium 4 processors based on the .13 micron Northwood core. These findings flew in the face of tradition, as a die shrink usually yielded processors that would run at higher clock speeds and consume less power. But the Prescott core wasn't a simple die-shrunk Northwood. The Prescott architecture consists of millions of more transistors than Northwood and it has a deeper pipeline. The combination of building a new core on a relatively new and unproven manufacturing process, and the increased power leakage that inevitably comes from shrinking the gaps between CPU traces are what resulted in Prescott's power hungry nature.
At about the same time that the news of Intel's difficulties with the .09 micron Prescott was spreading, IBM was contending with similar issues with the .09 micron PowerPC based G5 processors used in Apple's high-end Macintosh systems. Apple had claimed that the G5 would hit 3GHz within a year of its launch, but to this day IBM hasn't been able to deliver a CPU that runs reliably at over 2.5GHz for an extended period of time. And even at 2.5GHz Apple had to resort to using a custom water cooling solution to keep the CPU temperature under control. These developments led most people to believe that transitioning from .13 micron down to .09 micron was going to be troublesome for all chip manufacturers, regardless of architecture. But we still hadn't heard from AMD at that point.
AMD has since released some Athlon 64 processors built using their .09 micron Silicon On Insulator (SOI) manufacturing process. These CPUs are based on the Winchester core which is essentially nothing more than a die-shrunk Newcastle. There were some rumors that AMD's first .09 micron processors would incorporate some enhancements to the memory controller and support for SSE3 instructions, but that doesn't seem to be the case. Winchester is just a "smaller" Newcastle. We recently had the chance to test a .09 micron Winchester core based Athlon 64 3500+, so we decided to see how it matched up against a .13 micron Athlon 64 3500+ based on the Newcastle core. We weren't interested in gaming or general performance though. Both of these processors perform at identical levels. What we wanted to investigate was whether or not the Winchester core had a significant amount of overclocking headroom, and whether or not it ran hotter and consumed more power than a similar .13 micron CPU...
To compare the overclocking potential, thermal characteristics, and power consumption of our .09 micron - Winchester core based Athlon 64 3500+, to a .13 micron - Newcastle core based Athlon 43 3500+, we had to take some precautions and avoid a few pitfalls to ensure the comparisons would be legitimate. First off, we tested each processor in the exact same test bed; only the CPU itself was swapped between tests. The room where the testing was conducted is climate controlled, and remained at a constant 70oF (21oC) throughout. We used the exact same heatsink and fan combo, and the same thermal compound on each CPU. And the fan mounted to the heatsink was connected directly to the system's PSU, to prevent it from thottling at lower temperatures. The tests were conducted with all components mounted in a mid-tower case, but with one side-panel removed. The MSI K8N Neo2 Platinum motherboard we used for testing was updated to the latest BIOS (v1.4), all voltages and bus speeds were set manually, and Cool 'n Quiet was disabled.