AMD Phenom II X6 1090T Black Edition review

Having witnessed the awesome processing power of the Intel Core i7-980X, we were stuck with just one problem – its equally awesome asking price of £800. Now only weeks later, AMD may have ridden to the rescue of those requiring six-core performance, but who can't afford to spend the price of a whole new PC in a single chip.

The Phenom II X6 1090T is the first and most powerful of AMD's six-core line up. Despite this it only costs a fraction of the price of the 980X, at £240 inc VAT. As the Phenom II name suggests, though, this chip has a very similar architecture to the company's current range of processors.

It still uses a 45nm manufacturing process, compared to the 980X's more efficient 32nm process. Of course there are two extra processing cores here, each with its own L2 512KB instruction cache. However, the shared L3 cache remains at 6MB, the same as on Phenom X4 chips. This means there's less cache per processor, though the shared nature of the cache should mean that this isn't a huge handicap when dealing with the kind of parallel processing tasks that multi-core chips excel at.

One key new feature is AMD Turbo Core Technology. This works in a similar manner to Intel's Turbo Boost, introduced on its LGA1156 Core i3/i5/i7 processors. The AMD version is less flexible, however. It runs at its listed clock speed when using all six cores, but can boost clock speeds by up to 400MHz by disabling three of these. This is a less dynamic system than Intel's, which can boost with any number of cores, balancing out the boost between all the cores as long as overall heat is kept within specified limits.

In our testing, unfortunately, we never saw any evidence of Turbo Core at work – despite trying with two different motherboards, playing with BIOS settings and consulting other publications at Dennis. We tried a number of programs to monitor the clock speed but it didn't budge above the usual 3.2GHz.

Keeping in mind the lack of Turbo Core, benchmark results were about what we'd expect. It was roughly as fast as the fastest Phenom X4 in our single-threaded image editing test; but pulled away in multi-threaded apps like our video encoding test with an impressive 139, compared to the Phenom X4 955's 123.

It's powerful then, if given the right task, but even in video encoding it's beaten by some of Intel's quad-core chips. A Core i7-860 for example scores 164 in that test, thanks partly to its Hyper-Threading which doubles the number of addressable cores the operating system can see, but yet costs less at around £220 inc VAT. An overall score of 125 doesn't justify the X6's price when compared to other processors either. A Core i5-750 can be bought for under £150, and scores 139 overall in our tests.

If you have a 7-series AMD board, then you'll need to check with the manufacturer to see if a BIOS update is available. If so, and you need more parallel multi-core processing power, then an X6 chip would be a hassle free upgrade. However, you're not going to get a lot more performance overall, and even in multi-core tasks it's not that much quicker than far cheaper X4 processors.

If you need to buy a new motherboard to go with your X6, then forget it. In this case we'd recommend switching to Intel and building a Core i5 or i7-based PC instead, as it will be faster and cheaper.