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FX Vs. Core i7: Exploring CPU Bottlenecks And AMD CrossFire

Power And Efficiency

Today is AMD’s big chance to prove the value of its FX-8350 in a gaming environment, particularly with a price tag far lower than the competition from Intel. You see, it might appear that Intel has an advantage in our test because we picked its highest-end Ivy Bridge-based chip (the same opportunity given to AMD, by the way). But the price difference between the two doesn't escape us. Intel will need to justify its higher price in relation to the FX-8350.

But first, a look at power consumption and efficiency.

The FX-8350's stock power consumption doesn't look too terrible compared to Intel's, even though it's indeed higher. But we don't get the whole story from this chart, either. We didn't see AMD's chip running at its rated 4 GHz when it was under duress at stock settings. Rather, it dropped both its multiplier and voltage level under an eight-thread Prime95 workload to stay within its rated power envelope. Throttling artificially curbs the CPU's power consumption, and the big increases we see when the Vishera-based processor is overclocked come from fixed multiplier and voltage settings.

At the same time, games don't really utilize the FX-8350's ability to handle eight threads concurrently, and consequently never seem to trigger the same throttling mechanism. Also interesting is that the FX-8350, at its stock voltage setting, often exceeds the 1.35 V we set manually for overclocking. That explains why system power consumption doesn't change much between the stock and overclocked GPU load tests.

As mentioned, the stock FX-8350 doesn't throttle at all during gaming, since most titles aren't able to fully tax the chip. In fact, games actually enjoy a benefit from Turbo Core technology, which takes the CPU to 4.2 GHz. AMD’s biggest problem in the performance chart, then, is that Intel walks away with a noticeably higher average.

Using the average power consumption and average performance of all four configurations as the average for our efficiency chart, AMD's FX-8350 generates around two-thirds as much performance per watt compared to Intel's Core i7-3770K. If you’d like to run these calculations yourself, please note that we zeroed-out the average by subtracting one (100%) from the charted values.

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.