Four of AMD's Socket AM2+ Phenom X4 CPUs are represented in this year's CPU Labs test, ranging from the Phenom X4 9350e to the power-hungry Phenom X4 9950 Black Edition. Each Phenom X4 has four 65nm Agena cores, as opposed to the 45nm Deneb cores featured in the Phenom II X4. They also have a three-tier cache system, with each of the four cores sporting 128KB of Level 1 cache, 512KB of Level 2 cache and 2MB of Level 3 cache shared between the four cores. Clock speeds range from 2GHz for the 9350e to 2.6GHz for the multiplier-unlocked 9950 Black Edition.
Despite having four cores, the Phenom X4s aren't particularly fast, with the 9350e recording a score of 1,045 in the video encoding test - significantly slower than the triple-core Phenom II X3 720 Black Edition and all of the Core 2 Duo E8000-series CPUs.
Due to their low clock frequencies, they also performed very poorly in the image editing and multitasking tests. As a result, their overall scores were poor - so much so, in fact, that the 9350e is slower than some of AMD's earlier and less expensive dual-core Athlon X2 CPUs.
The lacklustre performance continued in games, with none of the Phenom X4 CPUs able to pull ahead of the Phenom II X3 or Athlon X2 CPUs. In Flight Simulator X, the 9950 Black Edition managed a minimum frame rate of 10fps, which was equalled by the significantly cheaper Athlon X2 7750 Black Edition. The latter was also able to keep up in Crysis, with a minimum frame rate of 22fps, which is the same as the 9950 Black Edition. Matters were worse at the bottom end of the series, with the £51 Athlon X2 4850e matching the 9350e's minimum of 8fps in Flight Simulator X. This is bad news indeed, considering that the 9350e costs nearly three times as much, retailing at £143.
At stock speeds, the Phenom X4s also draw a significant amount of power. The only CPUs that draw as much power are the Core 2 Extreme QX9770 and three Core-i7 CPUs, but these CPUs are vastly superior in terms of performance. The 9350e might appear to live up to the energy-efficient 'e' in its name, but given that its clock speed is considerably lower than those of any of the other Phenom X4s, the system's maximum power draw of 173W isn't that low compared with the 9750, which drew 205W but has a 400MHz higher clock speed.
Perhaps due to their high power consumption, the Phenom X4s were even less overclockable than the Phenom X3s. The 9950 Black Edition's overall score only increased from 907 to 997 when we increased its clock speed from 2.6GHz to 2.9GHz. The boost in games was equally disappointing, with the minimum frame rate in Flight Simulator X increasing from 10fps to just 12fps, and in Crysis from 22fps to 23fps. X3: Terran Conflict also saw little benefit, with the minimum frame rate increasing by 1fps.
As if the poor overclocking performance isn't bad enough, an overclocked Phenom X4 CPU practically draws enough power to light a house. The 9950 Black Edition in particular was as toasty as a slice of Kingsmill in the morning, drawing an eye-watering 320W. The 9850 Black Edition is even worse - when overclocked, it has killed the VRMs of seven Socket AM2+ motherboards in the lab over the past few months.
Everything about the Phenom X4s is decidedly cringe-worthy; they draw a huge amount of power, offer poor performance, especially in games, and lack overclocking headroom. Despite being released several years after AMD stopped developing the Athlon X2 series, and costing more than twice as much, they're often slower. If you're upgrading an old Socket AM2 system that's compatible with Socket AM2+ then the Phenom II CPUs are a far better buy. If you're building a new system, though, a Core 2 Duo or Core 2 Quad is superior in every way.
Author: James Gorbold & Antony Leather
AMD Phenom X4