AMD Athlon II X4 635 review

AMD keeps turning out CPUs with different configurations of clock speeds, cores and cache, to the point where it seems that soon every possible combination will be on the market. Not every combination can be a winner, however.

This latest Athlon II is a case in point: it’s generously endowed with four physical cores, but then hobbled by the absence of an L3 cache. The net result is, predictably, mediocre performance: running at a stock speed of 2.9GHz on a Vista system with 2GB of RAM, the X4 635 delivered an overall benchmark score of just 1.55. That’s fine for everyday applications – we regularly recommend laptops with half the performance. But compared with most of Intel’s Core i3 range it’s off the bottom of the chart.

In fairness, the Athlon II X4 635 is at least within sight of the low-end Core i3-530, which scored 1.58 overall. It even beat that chip in our 2D graphics test, scoring 1.92 against the Core i3’s 1.72. It narrowly won in the multitasking test too, scoring 1.75 versus 1.74. But, since the Athlon has four real cores, while the i3 relies on doubling up its twin cores with Hyper-Threading, the thinness of the Athlon’s victory is telling.

In our other tests the Athlon was a clear loser, managing only 1.13 and 1.40 in our Office and encoding exercises, while the i3 scored 1.29 and 1.56 respectively. Since the two chips are almost identically clocked (the Core i3-530 runs at 2.93GHz), you have to conclude that Intel’s baby is simply better engineered.

Predictably, the Core i3’s 32nm architecture brings lower power demands too, idling at just 31W on our LGA 1156 test system and peaking at 79W. Our Athlon system, running on a motherboard with integrated ATI Radeon 4290 graphics, idled at 55W, rising to 113W when we pushed it hard.

If AMD’s chips don’t match the technical sophistication of their rivals, the company generally makes it up with aggressive pricing, but right now you’ll pay more for an X4 635 than for an i3-530, and it’s not even competitive with AMD’s own Phenom II X2 555. Sure, that model has only two cores, but with a healthy 6MB L3 cache and a faster clock speed it’s still faster in our benchmarks, and £16 cheaper.

All told, the Athlon II X4 635 is a chip with little going for it. Don’t be tempted by its four cores: you’ll get more performance for your money elsewhere.