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AMD FX-8150: The Bottom Line

AMD FX-8150 Review: From Bulldozer To Zambezi To FX
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So, let’s say someone puts Core i5-2500K and FX-8150 in front of you. The Core i5 costs $220 bucks, and the FX runs $245. Which one do you buy?

If it’s me, I’m going with the Core i5. I gave the -2500K a Tom’s Hardware Recommended Buy award back in January, and I stick by that recommendation almost a year later.

In the very best-case scenario, when you can throw a ton of work at the FX and fully utilize its eight integer cores, it generally falls in between Core i5-2500K and Core i7-2600K—which is where it should appear all of the time given a price tag between those two most relevant competitors. Sometimes FX manages to outperform the higher-end -2600K, but other times it’s embarrassingly bested by its predecessor in threaded workloads.

Toss a single-threaded app at the processor, though, and it underperforms Intel's three-year-old Core i7-920 running at its stock 2.66 GHz. AMD’s architects say they shot to maintain IPC and ramp up clock rate, but something clearly went wrong along the way.

Ironically, consistent, scalable performance is one of the attributes that AMD claims it gets from its Bulldozer module. The issue we see over and over, though, is that it relies on software able to exploit scalability in order to compete. When it doesn’t get what it wants, performance steps back relative to the previous generation. As a result, even though AMD implements a more advanced version of Turbo Core to help improve single-threaded performance, the difference between what you get in lightly- and heavily-threaded applications is anything but consistent.

AMD validly points out that Bulldozer is an architecture in its infancy accompanied by an aggressive roadmap. It incorporates future-looking ISA enhancements and a layout clearly conceptualized with threaded software in mind. Performance in the applications able to take advantage of those considerations is fair in light of AMD's asking price. But the compromises made elsewhere don't justify $245, in my opinion.

Is Bulldozer A Good Foundation?

AMD projects 10 to 15 percent performance gains per year for the next several years. Just as important as what the company does architecturally, though, will be how software continues to evolve. Given its modularity, expect the engineering team behind Bulldozer to ramp up performance through a combination of more frequency, critical improvements to IPC, and optimizations to power.

We’ve seen how well-threaded workloads let FX-8150 step right up to Sandy Bridge, and we’ve seen how the processor falls on its face in apps that clearly weren’t written for the “go wide” approach to procuring performance. Piledriver, expected next year, should derive at least some of its advantage from IPC-oriented fixes. Consider those absolutely critical to evening out this architecture's idiosyncrasies.

But by the time it emerges for the enthusiast market, AMD will probably have to contend with Ivy Bridge, armed with advancements of its own. This isn’t a good thing. I want to see competition—a battle that keeps both Intel and AMD innovating. Does today’s FX invoke the Athlon 64 FX-51 that compelled Intel to rebadge a Xeon and come up with the Extreme Edition moniker back in 2003 just to compete? Not really, no. In fact, the chip giant didn’t have to do anything at all. Its nearly year-old 95 W parts fend for themselves without even a price adjustment.

Although I’m counting on Valencia and Interlagos to fare better against Xeon in the server space, where threaded workloads are the rule, it’s disappointing to see Zambezi suck down the power of Intel’s highest-end processors under load, perform like its competitor’s year-old mainstream chips, and wear the branding of a family that, eight years ago, actually made Intel squirm.

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