Verdict: More silicone than Pamela Anderson's cleavage
It's only the first month of the year, and already AMD and Intel have launched new processors, the Athlon 64 FX-60 and the Pentium Extreme Edition 955. Unfortunately, both chips are at the least interesting end of the CPU spectrum - the extreme high-end. They're ludicrously expensive, and in terms of clock speeds, disappointingly, they aren't much quicker than current high-end CPUs such as the Athlon 64 X2 4800+ and Pentium D 840.
Yet both are flagship products carrying the premium brand name of their respective companies. The question is, in the wake of the bargaintastic, super-overclocking Socket 939 Opteron 1-series, is it worth shelling out for the FX or Extreme labels?
The Athlon 64 FX-60 is the first dual-core Athlon 64 FX CPU, and it runs at 2.6GHz. Each core is equipped with 128KB of Level 1 cache and 1MB of Level 2 cache, and supports all the latest CPU technologies such as AMD64, SSE3, Cool n Quiet and Enhanced Virus Protection. Like previous FX chips, the FX-60 has a 200MHz FSB and a fully unlocked multiplier, so all you have to do when overclocking is increase the multiplier to over and above its default setting of 13. Quite frankly, on paper, the FX-60 is more than a little disappointing, as it's only one speed grade faster than the Athlon 64 X2 4800+, which runs at 2.4GHz. To justify the price difference, AMD really needs to do more to differentiate the FX family from the X2 family, especially as it's so easy to overclock an X2 4800+ to 2.6GHz just by raising its FSB to 217MHz.
The Pentium Extreme Edition 955, on the other hand, is more than just a speed bump over its predecessor, the Pentium Extreme Edition 840.
Under the surface, the 955 is a very different beast from the 840, as it's the first Intel CPU to be built on the smaller 65nm manufacturing process. This means that it requires less voltage and, clock-for-clock, runs cooler than the 840, which is made on a 90nm process. However, as the 955 runs at a higher frequency than that of the 840 - 3.46GHz compared to 3.2GHz - it has the same 130W TDP (Thermal Design Power).
The 955's speed increase was achieved with a 266MHz FSB (1,066MHz effective), as opposed to the 840's 200MHz (800MHz effective) FSB, so, providing you have suitable DIMMs, the 955 can handle more memory bandwidth than the 840. The 955 also has double the cache, with each physical core having its own 2MB of Level 2 cache. Like the 840, the 955 has a fully unlocked multiplier, so it's easy to overclock. It has two physical cores and two virtual Hyper-Threaded cores, so it can process four instructions simultaneously. All the latest CPU technologies are also supported: SSE3, EM64T, EIST and Execute Disable Bit.
The 955 also introduces a new catchphrase into the CPU dictionary - Intel Virtualisation Technology, which is just as spurious as it sounds. Intel's official marketing line describes Virtualisation Technology as the ability 'to run multiple operating systems and/or applications in independent partitions or environments for improved security and remote manageability'. Sounds exciting, doesn't it? Perhaps it would get an IT manager excited but I can hardly see it getting enthusiasts all worked up into a sweat.
PERFORMANCE
To benchmark the FX-60 and 955, we built two test PCs, the specs of which are listed in the results table opposite. Although these CPUs are designed and marketed with overclocking in mind, we started off by testing each chip at its default frequency setting. The 955 was the first to finish its run through the Custom PC Media Benchmarks with an overall score of 1.21, noticeably slower than the Athlon 64 X2 4800+ tested in last months CPU megatest. Not an auspicious start for Intel's latest and greatest. Worse was to follow for the 955, as the FX-60 finished the same benchmarks with an overall score of 1.53. Yes, in other words, the FX-60 is more than 26 per cent faster than the 955 in our tests. A closer examination of the benchmark results shows that of the three tests that comprise the Media Benchmarks, the 955 could only hold its own in the video encoding test, a traditional strong point for Intel's NetBurst architecture CPUs.
We also tested each CPU in Doom 3, only to find the same pattern that we saw in last month's CPU megatest. In other words, modern 3D shooters aren't CPU-limited, they're GPU-limited. In more CPU-limited strategy games, such as Rome: Total War, the FX-60 pummelled the 955 into the ground beneath its feet, averaging a 42 per cent higher frame rate.
However, you'd be a fool to buy any Athlon 64 FX or Pentium Extreme Edition and not overclock it, so we unleashed the voltage and multiplier settings in each test system's motherboard BIOS to see how far we could push the FX-60 and the 955. By increasing the vcore of the FX-60 from 1.35V to 1.565V, it was happy to run with the multiplier boosted from 13 to 15. With each core now running at 3GHz, 400MHz faster than their default 2.6GHz, the FX-60 screamed through the Media Benchmarks with an overall score of 1.73. Unfortunately, although it would POST at 3.2GHz (with a multiplier of 16), the FX-60 wouldn't load Windows at this frequency, even with a further vcore increase. A 400MHz overclock on each core to 3GHz sounds good, but to be honest, the FX-60 is very disappointing when you consider that the Athlon 64 X2 3800+ will overclock to 2.8GHz, and costs much less.
Overclocking the 955 proved even easier than it was with the FX-60, as it has a very low default multiplier, thanks to its 266MHz FSB (1,066MHz effective). The 955 has a default vcore of just 1.3V, and we only had to increase this to 1.45V to get it to run perfectly stably at a massive 4.53GHz by raising its multiplier from 13 to 17. Unfortunately, at these settings, the thermal throttling kicked in after a few minutes, which actually slowed down the 955's performance. As we didn't have a phase-change cooling system to hand, we had to resort to testing the 955 at 4.26GHz, with a vcore of 1.35V and a multiplier of 16. At these settings, the thermal throttling remained in its kennel where it belongs, allowing the 955 to bulldoze its way through the Media Benchmarks with an overall score of 1.48 - 22 per cent faster than its out-of-the-box score. This massive overclock also boosted the 955's frame rate in Rome: Total War by 16 per cent, although it still lagged behind the FX-60, at stock clocks and during overclocking.
CONCLUSION
While the FX-60 is the fastest 'out-of-the-box' dual-core CPU in production today, it's really only one speed grade faster than the much cheaper Athlon 64 X2 4800+, which is just as overclockable. This really sums up the principal problem now bedevilling the Athlon 64 FX brand: there really isn't anything to justify the price difference between it and the Athlon 64 X2 line-up.
Although the 955 is much more overclockable and runs cooler than the 840, it suffers from many of the same problems. Because it 'only' runs at 3.46GHz, its stock performance is laughable, given the cost, while the super-long pipeline NetBurst architecture means it only really excels at video encoding. Any other type of application, especially CPU-dependent games, are seriously laggy on the 955 compared with the FX and X2.
Until Intel gets its P6 and NetBurst combined architecture CPU out of the door later this year, you'd be far better off buying and overclocking an Athlon 64 X2 3800+, or a Socket 939 Opteron 1-series CPUs, rather than investing in either of these so-called 'super-chips'.
