Verdict: Conroe is here, and it's awesome, unless you work for AMD
The human race has invented many ways of describing speed, some of my personal favourites being 'schnell' (German), 'veloce' (Italian) and 'rapido' (Portuguese). However, we may need to create another word to describe the speed of Intel's 2.93GHz Core 2 Extreme X6800. How about kryptoturbopolyzoomwell?
In most regards, the Core 2 Extreme is architecturally identical to any Core 2 Duo CPU. So, like Core 2 Duo, it's an LGA775 chip, although you'll need to ensure that your motherboard adheres to the updated VRM specification, as some older 975X boards aren't compatible. It has two physical cores, each clocked at 2.93GHz, which share a unified 4MB Level 2 cache. Both cores share a quad-pumped 266MHz FSB (1,066MHz effective) through to the Northbridge. The Core architecture introduces support for SSE4 and a power-saving technology that automatically drops its frequency to 1.6GHz when the CPU isn't under heavy load.
However, apart from the 266MHz difference in clock speed, what else separates the 2.93GHz Core 2 Extreme X6800 from the fastest Core 2 Duo, the 2.66GHz E6700? As with the previous two Intel Extreme chips, the X6800 has a fully unlocked multiplier with a default of 11 (11 x 266MHz = 2.93GHz), although you can adjust this.
We already know that the 2.66GHz Core 2 Duo E6700 can beat the Athlon 64 FX-62 to a pulp, so we were keen to see how fast Intel's X6800 CPU is. Installed in an Intel D975XBX motherboard with 2GB of Corsair XMS2-8500 RAM and a GeForce 7900 GTX, the X6800 set new records in all three sub-tests that comprise the CPC Media Benchmarks. Its Paint Shop Pro image editing score of 1.95 is nearly 22 per cent faster than that of an Athlon 64 FX-62, while it was 21 per cent faster at video encoding and 10 per cent faster at multitasking. These are amazing differences, given that the benchmarks are designed to test the whole system, not just the CPU. The X6800 is also great at gaming - its average frame rate in Need for Speed: Most Wanted was 14fps higher than the average frame rate of the Athlon 64 FX-62.
While the 2.93GHz Core 2 Extreme X6800 is fast, you'd be foolish not to overclock it. After all, you could build a PC just as fast, and save yourself £350 by buying a 2.66GHz Core 2 Duo E6700 and overclocking it to 2.93GHz. We initially tried overclocking the X6800 by increasing its multiplier to 14x, which boosted its internal frequency from 2.93GHz to 3.73GHz but, even with the vcore at 1.6V (the maximum provided by the motherboard), it wasn't stable enough to complete all of our benchmarks. We then dropped the multiplier to 13x, making it run at 3.46GHz, at which it was fully stable.
However, as the X6800 was nearly stable at 3.73GHz, we reckoned it would benchmark higher than 3.46GHz, so we dropped the multiplier back to 11x, but upped the FSB from 266MHz to 333MHz, which raised the internal frequency to 3.66GHz. At this speed, with the RAM set at a 2:3 ratio with the FSB, so it ran at 1GHz, the X6800 set a new record in practically every benchmark we tried. For example, its video encoding score was 31 per cent faster than that of a phase-change-cooled Athlon64 FX-60 running at 3.49GHz, and 25 per cent faster at multitasking. In fact, the only system we've tested that was faster at video encoding was the dual Xeon 5160 system we tested last month, as it's able to process four threads simultaneously.
CONCLUSION
All Intel Extreme series and AMD Athlon 64 FX series chips are fast, but they've never been able to justify their price premium. With the Core 2 Extreme X6800, Intel has, for the first time, made a special-edition CPU that's worth its enormous price tag. It's ludicrously fast at its stock 2.93GHz frequency, and insanely fast when overclocked. Even better, you don't have to spend a small fortune on a helicopter-like, phase-change cooling system to make the most of the X6800, as it's extremely overclockable, even with air cooling.
