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Hoping The Best Is Yet To Come

AMD A10-7850K And A8-7600: Kaveri Gives Us A Taste Of HSA
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AMD deserves praise for championing heterogeneous computing, and doing it in a way that opens up the benefits to multiple market segments, hardware vendors, developers, and ultimately a larger number of end users. Even as Intel increases the footprint of the graphics engine on its own processors and shores up driver support for compute, AMD gets most of the credit for pushing forward with OpenCL evangelization.

The real purpose of Kaveri is encapsulated in this diagram. Leveraging the right resources for any given workload can have a profound impact on performance and power—it just takes developers optimizing for the potential available in today’s GPUs.

Unfortunately, much of our benchmark suite (just like today’s software landscape) isn’t put together with those resources in mind. We started folding in OpenCL-capable tests a long time ago, and we currently have a number of metrics able to expose the benefits of GPU acceleration. Even those tasks didn’t shine brightly on Kaveri today, though. Despite the lack of innovation we’ve seen from Intel on the PC desktop, its Haswell architecture cuts through most tasks faster and at lower power than what AMD is showing.

Of course, the notable exception is in the gaming space. Intel does have an ace in its Iris Pro graphics, but charges far too much for them and is very limited in exposing the GT3/GT3e implementation of its GPU. That leaves the door open for AMD to kick HD Graphics 4600 around, which it does. Even the 45 W version of A8-7600 has no trouble trouncing Intel's 84 W Core i5-4670K. The difference between them is made more significant when one pumps out playable frame rates and the other cannot.

AMD was pretty explicit that it designed Kaveri to fit in thermal envelopes from 15 to 95 W, but that it optimized for the middle of that range. Today’s numbers confirm the company’s assessment.

A10-7850K, the 95 W flagship, is a capable little gaming processor. It should be able to handle most games at 1920x1080 using decent detail settings. Thanks to a 512-shader GCN-based graphics engine, it’s faster than A10-6800K. But when you switch over to the other desktop-oriented workloads in our test suite, it merely trades blows with Richland’s top-end model. But expect to pay an extra $30+ for it (AMD says the -7850K will sell for $173, though it hasn’t shown up for sale on Newegg yet). And you’ll need a Socket FM2+-equipped motherboard, too.

Personally, I’d go for a $75 Athlon X4 740 and a Radeon HD 7750 for close to the same amount of money…at least until HSA-optimized software gives us a reason to favor Kaveri-based APUs.

There’s a lot more to get excited about at the 65 and 45 W power levels. AMD’s bias to the GPU is evident in games where the A8-7600, constrained to a 45 W TDP, destroys the 84 W Core i5 with HD Graphics 4600 and its own 45 W A8-6500T. Kaveri doesn’t have to lean on games, either. Its application performance is quite a bit better than the similarly-priced Richland-based APU we used for comparison. The caveat is that Intel does the low-power, high-performance song and dance more convincingly.

With its emphasis shifting away from big desktop CPUs, and even the 100 W APUs it used to herald at the top of its stack, AMD appears most focused on 65 W and lower. That’s probably not what performance-hungry enthusiasts want to hear, but with significant real-world gains in graphics and general-purpose computing, Kaveri looks to be stronger mainstream desktop and mobile contender than Richland.

The story of this APU isn’t opened and closed today. AMD is championing the Heterogeneous System Architecture, and Kaveri represents the pinnacle of its work so far. Although we have a better idea of what HSA might enable, there is still a lot of work to be done on the software side. And with OpenCL 2.0 recently ratified, we’ll only start scratching the surface in 2014.

And so we step away from Kaveri marveling at the SoC’s potential and eager for developers to start pushing out optimized apps, but lacking a real reason to make a purchase today. Fortunately, this platform doesn’t have to be programmed to specifically. AMD just needs ISVs to adopt OpenCL 2.0. From there, the merits of HSA should become more apparent. We look forward to watching the saga unfold.

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