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Bulldozer: Improvements Are Urgently Needed

AMD FX: Energy Efficiency Compared To Eight Other CPUs
By , Achim Roos

Our article AMD Bulldozer Review: FX-8150 Gets Tested thoroughly explores the technical details of AMD's general architecture and the products that emerge from it. It sheds light on the design, performance per core, power management, second-gen Turbo Core, and potential improvements in Windows 8, which is aware of AMD's architecture and can optimize for it.

However, the conclusion is crystal clear: there are very few arguments in favor of the FX CPU right now. Performance improvements above and beyond the Phenom II X6 are limited to heavily-threaded applications. In case of modern applications that don't utilize multiple threads, this Bulldozer digs its own grave. The only way to properly utilize the FX processor is to run applications able to tax its eight integer cores.

But today’s topic is energy efficiency, measured in performance per watt of consumed electricity. This is where AMD had a real chance to shine, given its move from 45 nm manufacturing to 32 nm lithography. The company also made significant improvements to the way its architecture cut power use, employing power and clock gating to minimize waste. Energy could have been saved and, assuming performance comparable to last generation's hardware, efficiency would still get a nice boost. 

Our own suite of tests includes a number of single- and multi-threaded applications, all updated to the latest versions possible. Run as scripted suited, they give us a general picture of efficiency that doesn't frame AMD's FX processors in a very positive light. In spite of a higher clock rate and more cores, the effective performance per clock cycle is, as we all know, lower. A higher frequency does not translate into substantial efficiency gains, even in the face of a more advanced 32 nm process node. Performance is adequate only when multi-threaded applications are run. As such, AMD is treading water with respect to efficiency, and we certainly wouldn't fault the AMD fans who continue buying Phenom II processors as a way to save some money.

On the desktop, efficiency probably isn't as important as it is in the enterprise space, where racks full of servers quickly multiply any weaknesses in power use. The FX doesn't seem to run any hotter than AMD's existing processors, and its performance is more or less ample even for power users. If you are, in fact, in the market for a platform upgrade, consider waiting to see what Intel's Ivy Bridge design will do. After all, FX would require you to buy a new Socket AM3+-equipped motherboard anyway. Ivy Bridge will see Intel introduce its 22 nm manufacturing process, hopefully dropping power use even as the company increases performance.

In order for AMD to compete with that architecture, its forthcoming Piledriver design needs to incorporate significant improvements to IPC and power. Incidentally, the company claims that both are set to receive some attention. Until then, we'd hope to see AMD dropping the prices on FX to get us interested.

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