Phenom II X3 720 Black Edition review

Could three be the magic number the second time around? If you've been following the online cacophony kicked up by AMD's new Phenom II X3 processor, you might well think so.

You may also recall that AMD's triple-core chip is nothing more than a quad-core chip with one core disabled.

That's not news. The fuss all started when a Korean PC enthusiast discovered it was possible to spool up the dormant core on the new 45nm version of AMD's X3 chip via the toggling of a BIOS option.

Four cores for the price of three, what's not to like?

Superficially, absolutely nothing. However, on closer inspection, there are a number of catches. For starters, you need a chip where the stepping code starts with the numbers 904.

You must also have an AMD 790FX motherboard with an AMI-based BIOS. If that wasn't specific enough, that AMI-based board must also be made by either Biostar or Asrock.

If you have the required kit, just hop into the BIOS, enable Advanced Clock Calibration in the CPU features and watch your triple-ganger go four-way. After that, you may find you have a stable quad-core system, or you may not. Many X3 chips are triple core for good reason.

In other words, there's something rotten about the disabled core. You can enable it by all means, just don't assume it will work.

Sadly, we can't report any first hand experiences of this sleight of silicon. However, what we can say is that the X3 is a great little chip regardless of any of these core-enabling larks. Just like the recent 45nm Phenom II X4, the new X3 model is an absolute whore for high frequencies.

Overclocking monster

Our 720 Black Edition sample was stock clocked at 2.8GHz, but we had it humming a 3.7GHz tune within minutes of booting. Spend an afternoon fiddling and you can probably add at least 200MHz to that figure.

The upshot of all this is that an overclocked X3 comes remarkably close to matching the performance of a stock clocked X4 chip in highly multi-threaded apps.

Even better, though, is its performance in apps that don't scale particularly well across multiple cores and respond well to raw clockspeed. Yup, you guessed it: games!

If, therefore, you're on the lookout for a dirt-cheap gaming CPU that also has adequate multi-threading chops, you could do a lot worse than the Phenom II X3.

The fact it drops into both existing AM2 motherboards as well as the latest AM3 socket, thus supporting both DDR2 and DDR3 memory, only adds weight to its appeal.