The latest Advanced Micro Devices CPU to hit the market relies on the good old trick of increasing the clock speed to raise performance levels. AMD’s new champ is the Phenom II x4 955 Black Edition, which is set to supersede the Phenom II x4 940 Black Edition as AMD's new top-of-the-line processor.

We took a quick look at the 955 to see if it does push the performance envelope an appreciable amount and found that, under initial testing, the 955 is some 15 percent faster than the 940. We took a very straightforward approach to testing the 955; we simply yanked out the 940 in our AMD test system (see "AMD Guns for Intel's Nehalem with the Phenom II")  and replaced it with the 955.

Our test system uses an ASUS M3A78-T motherboard, which required an update to the latest BIOS to support the 955. The M3A78-T is an old standby and was developed during the days of AM2+ sockets. Of course, there are newer motherboards on the market, which offer DDR3 RAM support and other features that can squeeze a little more speed out of the 955 (and even the 940) Phenom II CPUs. But by using the M3A78-T, we were able to create the most level playing field possible.

We tested the Phenom II x4 955 using the 64-bit version of Performance Test 7.0 from Passmark. Our test operating system was Windows Vista 64-bit Ultimate edition. With the 955 in place, the system offered an overall Passmark score of 1056.7 and a CPUmark score of 4,019.7—a decent improvement over the 940, which scored 904.1 and 3,348.6, respectively.

Using the newest version of AMD’s Overdrive utility, we were able to experiment with different clock speeds on the 955 and found that, with our test system, we were able to run the 955 at 3.8GHz reliably. That increased our Passmark score to 1,146.5 and our CPUmark score to 4,846.4, a worthwhile increase.

The Phenom II x4 955 Black Edition will be priced at $245, and AMD is aiming to have the CPU compete with Intel’s $270 2.83GHz Core 2 Quad Q9550, which has a CPUmark score of 4,196.1. A wise target on AMD's part, since none of AMD’s current processors can come close in performance to Intel’s Nehalem CPUs.

System builders should expect no surprises from the Phenom II x4 955 Black Edition, which in this case is a good thing. The CPU will quickly drop into current Phenom II configurations, making the transition to a faster CPU very simple, while cutting costs by a few dollars.