You've seen the performance results and probably have a sense of where things stand, but we can summarize them with more precision using one of our world-famous price-performance scatter plots. (We've omitted a few really expensive CPUs, because they tend to squeeze everything together, making the plot hard to read.)
The more desirable mixes of price and performance should be close to the upper left corner of the plot area, while the least desirable will be toward the bottom right. As you can see, the FX-8150 can't quite match the overall performance of the Core i5-2500K, and it costs $29 more, as well. That puts the FX-8150 in a difficult position purely from a value standpoint—without even considering that the Core i5-2500K fits into a smaller 95W power envelope. That leaves us pondering what exactly AMD was thinking when it priced the FX-8150 above the 2500K. Perhaps it's hoping to get some marketing traction from the FX's inherently bigger numbers—Eight cores! Higher clocks! Larger caches!—but those things don't count for much when it comes to delivered, real-world performance.
I'm also not entirely thrilled with the way the FX-8150 managed to edge so close to the Core i5-2500K in our overall performance index, with strong performances in certain types of widely parallel tests and some really rather weak showings in more typical desktop applications that use one to four threads. Bulldozer's performance characteristics could make a fair amount of sense for server-class workloads, but desktop users will probably always have to contend with some applications dominated by a nasty, branchy single main thread. In such cases, the FX chips aren't horribly weak, but they're sometimes no faster than a relatively cheap CPU like the Athlon II X3 455.
Faced with such results, AMD likes to talk about how Bulldozer is a "forward-looking" architecture aimed at "tomorrow's workloads" that will benefit greatly from future compiler and OS optimizations. That is, I am sure, to some degree true. Yet when I hear those words, I can't help but get flashbacks to the days of the Pentium 4, when Intel said almost the exact same things—right up until it gave up on the architecture and went back the P6. I'm not suggesting AMD will need to make such a massive course correction, but I am not easily sold on CPUs that don't run today's existing code well, especially the nicely multithreaded and optimized code in a test suite like ours. The reality on most user desktops is likely to be much harsher.
Speaking of harsh realities, the fact that such a large chip, at 315 mm², can't manage to keep up with Intel's much smaller Sandy Bridge silicon is really quite unfortunate. The hope for the Bulldozer architecture's success in desktop PCs now rests on a series of future possibilities, starting with the maturation of GlobalFoundries' 32-nm manufacturing process. We know AMD is having trouble shipping enough Llano chips to meet demand, and thanks to our overclocking exploits, we have a sense that FX-series processors may be up against process-related challenges, too. If those get fixed and AMD is able to squeeze several hundred megahertz or more into the same power window, maybe the FX series can improve its value proposition.
Beyond that, we know AMD already has working examples of the Trinity APU, whose "Piledriver" core includes improvements for both instruction throughput and power savings. The plan of record is for Trinity to be on the market before Intel's Ivy Bridge arrives next spring. An updated server and desktop chip based on Piledriver—a true replacement for Orochi/Zambezi—is slated for some time next year, as well. If AMD can deliver those chips in timely fashion and stick to its projected yearly release cadence, with the mysterious "Steamroller" and "Exacavator" scheduled for 2013 and 2014, perhaps this architecture will progress toward its true potential.
585 comments — Last by Arag0n at 4:45 AM on 11/24/11
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