Verdict: Faster than the G0 Core 2 Quad Q6600 in many tests.
The Core 2 Duo E8400 is based on the new 45nm Wolfdale core, which itself is based on the Penryn architecture. It's a dual-core chip with 6MB of Level 2 cache and a stock speed of 3GHz. You could argue that dual-core technology is old-school now but, in many applications, two fast-running cores will still beat four slower cores. Intel clearly hopes that we'll remember this, as the price of the E8400 is very close to that of the infamously overclockable G0-stepping £160 Core 2 Quad Q6600.
In our Media Benchmarks 2007, the E8400 performed extremely well at stock speeds. The score of 1,165 in the GIMP test compares favourably to the 878 of the Q6600. In fact, this score is slightly better than that of the £640 quad-core Core 2 Extreme QX9650, which is essentially two E8400s stuck together.
The E8400 also achieved a higher score than the Q6600 in the multitasking test, managing 1,168 compared to the latter's 890. This result may seem surprising, but it can be explained by the improved Penryn architecture of the E8400, and the fact that its two cores run at 3GHz by default, while the Q6600's four cores run at only 2.4GHz.
Video encoding was always going to favour the four cores of the Q6600, although they provided less of an advantage than we expected. The Q6600 scored 1,340 in our HandBrake test, while the E8400 scored a satisfactory 1,173. Satisfactory might seem an odd word to use, but this result is faster than that of the fastest AMD quad-core CPU we've seen, the £150 2.3GHz Phenom 9600, which managed just 1,100. Overall, our Media Benchmarks 2007 show that the E8400 is very fast, scoring 1,168 compared to the 1,036 of the Q6600.
The E8400 was also faster in SuperPi 1M, taking 15.502 seconds, while the Q6600 took 21.591 seconds. However, the multithreaded Cinebench R10 test favoured the Q6600, as it scored 8,778 compared to the 6,373 of the E8400. Supreme Commander was also faster with the Q6600 than with the E8400 - the Q6600 managed a minimum of 10fps and an average of 41fps, compared to the E8400's minimum of 8fps and average of 39fps.
With the E8400 installed in our test system, the PC sucked a maximum of 170W of power from the wall at stock speeds, while with the Q6600 we saw a peak of 254W.
With the Penryn architecture comes the promise of new and dizzying levels of overclocking, and we set about pushing the E8400 to its limit. Our E8400 had a vID of 1.15V, so we whacked up the CPU voltage of our Asus P5K Premium WiFi-AP to 1.45V to try our initial 450MHz FSB. This gave us a 4.05GHz CPU, and our Orthos full-load testing showed no errors.
However, we were continually thwarted as we tried to add extra speed. Increasing the FSB to 460MHz (for a 4.14GHz CPU) led to instability. We thought it was close to becoming stable, so we upped the voltage to 1.5V while raising the FSB Termination voltage to 1.3V and the Northbridge to 1.55V. This proved fruitless, although the CPU never ran hotter than 68ûC.
We returned to the stable 450MHz FSB overclock and benchmarked again. The GIMP test came in at a staggering 1,539 compared to the 1,292 that the Q6600 scored when it was overclocked to 3.6GHz. The multitasking score also gave the E8400 a big win over the overclocked Q6600, with an overclocked score of 1,455 to 1,159. The HandBrake video encoding score of 1,563 is respectable, although the quad-core Q6600 scored 1,981. This gave the E8400 an overall score of 1,455 and the Q6600 an overall score of 1,477, which isn't bad at all. Cinebench R10 also improved markedly to 8,559, while the SuperPi 1M time was slashed to 11.534 seconds. Supreme Commander ran quicker with the overclock too, although only by 1fps.
Overall, raising the clock speeds increased performance by 25 per cent, and the system drew just 222W at peak with this overclock. The Q6600 consumed more than this at stock speeds, which speaks volumes for the E8400's energy efficiency.
Conclusion
The Core 2 Duo E8400 is certainly fast, even compared with the Core 2 Quad Q6600. Only in heavily multithreaded apps do the Q6600's four cores provide a speed advantage. In other tests the E8400 dominates. However, there are two things to consider before you splash out. First, the £117 2.66GHz Core 2 Duo E8200 is a better buy if you're short of cash. The second is the imminent release of the 45nm Yorkfield Core 2 Quads, which will probably be very overclockable. However, we don't know when these will be available or how much they'll cost (pre-order prices put the 2.66GHz Core 2 Quad E9450 at £220 but this could change). If the E8400 is any indication, though, buying a Yorkfield Core 2 Quad will be like winning the World Cup.
