We started our overclocking attempts using AMD's Overdrive utility but very quickly encountered problems. The software was throwing up all sorts of false readings and generally just didn't seem to be stable so instead we resorted to overclocking through the BIOS.
We started out conservatively, upping the multiplier from 17x to 18x and giving us a total clock speed of 3.6GHz. This was completely stable so we continued onto 19x for a total clock speed of 3.8GHz. This also seemed pretty stable, booting into windows and starting some benchmarks, but after a short while it crashed. We therefore upped the CPU voltage to 1.5V and found this to be stable. Moving further on, we tried 19.5x and 1.55V to give us a stable 3.91GHz, which wasn't a bad start.
After this we started experimenting more and more until at one point we were able to start benchmarks at 4.19GHz (220MHz x 19) though it quickly crashed. With so many settings to play with we're confident that this could've been made stable but we ran out of time, to really fiddle with all of them and find the right balance, so we settled on calling 3.91GHz our best with this CPU. However, as is always the case with overclocking, the price you pay for more performance is more power consumption. We saw our idle system power consumption rise from 200W to 250W while load power consumption went from 288W to 340W.
In contrast, in our testing, Intel's closest competitor, the Q9550, overclocked to 3.4GHz, without any extra voltage and these CPUs have been known to push 4GHz with a normal air cooler. However, the sheer ease of overclocking of the 965 BE would make us opt for this chip.
Finally, we come to look at value, and it's here that the 965 BE really starts to make sense, even considering its middling performance. A decent AM3 motherboard can be had for about £70, while the 965 BE itself is going for about £180 making for a total system cost of £250. In contrast, the cheapest Core i7 motherboard you'll find is around £140 and the cheapest CPU is £205, making the system cost £345. A Core 2 system does match the Phenom II system for price but, considering that whole platform is being replaced within a matter of months and there are unlikely to be anymore CPUs made for it, we'd avoid plumping for it now.
The AMD Phenom II X4 965 BE is AMD's fastest ever CPU, in every sense of the word and it matches any CPU available for a similar price in terms of performance. Add in its unlocked multiplier to make overclocking easier and you have a CPU that should be worthy of recommendation. Unfortunately with Intel set to release its Core i5 CPUs in the next couple of months, and with early indications suggesting they'll be very fast, they may be worth the wait. But if you need a new, affordable chip now, AMD has you covered.