The Best Sub-£100 CPU

AMD Phenom II X4 955 Black Edition

Manufacturer: AMD
UK price (as reviewed): £89.98 (inc VAT)
US price (as reviewed): $119.99 (ex tax)

At £90, the Phenom II X4 955 Black Edition is one of the most expensive processors in this group test but you get a lot for your money. The processor is one of only three on test that has four physical cores, and these are based on the full-fat Deneb design too, so each receives 128KB of L1 cache and 512KB of L2 cache, while sharing a larger 6MB pool of L3 cache. Despite having four physical cores, the X4 955 BE runs at 3.2GHz – the second-highest frequency of the processors on test.

This should mean the CPU performs well, but having four cores and a high
clock speed also means a higher power draw; the X4 955 BE’s TDP of 125W is the highest of the processors here. This means that it requires a more powerful cooler than the other processors on test, limiting its use in areas where noise, power consumption or size are restricting factors, such as in small form factor or media PCs.

As with the other K10-based AMD processors, the X4 955 BE lacks an on-board GPU – if you don’t want to buy a discrete GPU, the only option would be to buy a motherboard with on-board graphics. Not surprisingly, given its resources and price, this AMD quad-core CPU performed well in our Media Benchmarks suite; its score of 1,213 was the fourth-fastest stock-speed result, behind the slightly more expensive Core-i3s and the cheaper Pentium G850. However, in both Cinebench 11.5 and WPrime – both of which reward core count and frequency – the X4 955 BE was peerless, coming top in both tests.

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Thanks to its high frequency and the fact that our two test games can take advantage of the extra cores on offer, the X4 955 BE was also competent at gaming. It was in the top four stock-speed results for every test, apart from the Arma II test at 1,920 x 1,080, where it mysteriously dropped down the rankings.

We expected the X4 955 BE to be a competent overclocker given that the Phenom II X4 980 BE, which is also based on the Deneb core design, sports a clock speed of 3.7GHz. We managed to push the X4 955 BE all the way to 4.2GHz by using a vcore of 1.565V and a CPU/NB of 1.235V. At these settings, the X4 955 BE jumped to the top of our Media Benchmarks table with 1,605 points. This jump was accompanied by a significant bump in power consumption, however – our test system drew 400W from the wall under full load, twice as much as the Core i3-2100, despite the latter being only 7 per cent slower.

There’s no doubt about the raw power of the X4 955 BE, but the Core-i3 2100 is nearly as fast and consumes less power. Its lack of an on-board GPU also makes it less flexible than the A8-3850.

Specifications

• Frequency 3.2GHz
  
• Core Deneb
  
• GPU N/A
  
• Number of cores 4 x physical
  
• Cache L1: 4 x 128KB, L2: 4 x 512KB, L3: 6MB
  
• Packaging Socket AM3+
  
• Thermal design power (TDP) 125W