Today we're going to focus on AMD's Athlon II X4 series that offers some very nice, affordable processors, no matter what kind of graphics you prefer: integrated or discrete.

Testbed Configuration

First, the test subjects.

There are many CPUs in the series now, each of different availability. For example, Athlon II X4 638, one of the most interesting, is hard to obtain. So today we'll try to get by with just two models: Athlon II X4 641 and Athlon II X4 651. The latter is actually very much identical to A8-3870K in terms of the CPU part, unlocked multiplier included. (AMD doesn't advertise this much though.) From the overclocker's point of view, Athlon II X4 651 is truly unique: there are simply no other CPUs for this kind of money that can be overclocked this easily. By the way, it's also the first Athlon Black Edition after a long break! The only fly in the ointment is Llano's moderate clock rate potential. Judging by the results obtained by our colleagues from other websites, this family's limit is around 3.5–3.6 GHz, even considering the 32-nm process technology. We tried it at the 3.6 GHz and stumbled upon stability issues. Even the 0.1 V voltage increase caused the CPU to crash while running some programs, the Corel Draw installer, in particular (stability test results were fine though). Only after we had reduced the clock rate to 3.5 GHz, everything started working without a hitch. For this reason, we decided to post such results as well, given how easy overclocking had been.

Now, the competitors.

Firstly, there's Athlon II X4 645, the highest-end Athlon II X4 for the Socket AM3. Many buyers tend to compare CPUs based on processor numbers. According to this logic, Athlon II X4 645 should fit right between Athlon II X4 641 and Athlon II X4 651. Let's see if it's so. Secondly, we'll take Pentium G850, even though, formally, it's been replaced by Pentium G860. The latter is more expensive than today's test subjects, while the former is on the same price level. Speaking of prices, Athlon II X4 645 isn't very cheap, mind you, being on a par with FX-4100 and Core i3-2120, so let's throw these in as well. These two belong to the higher-end segment, yes, but that makes a comparison with the overclocked Athlon II X4 651 even more interesting.

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