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AMD unwraps its seventh-generation desktop APUs and AM4 platform

Paving the way for Zen

AMD's Zen CPUs, code-named Summit Ridge, are set to arrive early next year, but there's a lot of groundwork to be done before those next-generation processors make their entrance. Way back in January, AMD announced it would be unifying its desktop platforms for its CPUs and APUs with a new socket—AM4. Now, motherboards and chipsets with that new socket are on the move toward retail. Yesterday, the company announced that desktop AM4 motherboards and its seventh-generation desktop APUs, code-named Bristol Ridge, are now available for its OEM partners.

For some background, today's AMD APUs require Socket FM2+ motherboards that are incompatible with their integrated-GPU-free CPU cousins, which still drop into Socket AM3+ motherboards. Each of those sockets has a range of associated chipsets, too, serving builders of all budgets. AM4 wipes away all of that cross-platform incompatibility with a single socket and motherboard lineup. Compatible APUs and CPUs will offer modern features like PCIe 3.0, DDR4 memory controllers, and support for NVMe storage devices on top of the new features that AM4-platform chipsets will include.

The first family of AM4 APUs, code-named Bristol Ridge—or "seventh-generation APUs," as you'll see them referred to in marketing materials—have been available in notebook PCs for a couple of months in TDPs ranging up to 45W. As a brief refresher, Bristol Ridge parts are built around AMD's Excavator CPU core and GCN 3.0 graphics technology, but improved process technology and lots of optimization work have allowed those chips to deliver modest improvements in performance over Carrizo parts on the same 28-nm process. More importantly, Bristol Ridge parts give us our first glimpse at how AM4 motherboards might look for Zen CPUs when they arrive next year.

The lineup
Back when Carrizo APUs arrived for notebooks, AMD brought that processor family's Excavator CPU core to the desktop with just one part: the Athlon X4 845, a 65W quad-core CPU without integrated graphics. That Athlon ran at 3.5GHz base and 3.8GHz boost clocks. In contrast, Bristol Ridge is a family of desktop APUs with Radeon graphics onboard, although one Bristol Ridge CPU will also be available in the form of the Athlon X4 950.

The extensive tweaking and tuning in Bristol Ridge is perhaps most evident in the specs of the top-end A12-9800 APU. Despite its 65W TDP, this chip's boost clock is only 100MHz short of the 4.2GHz the 95W A10-7890K can muster. The graphics processor on this chip also runs its 512 GCN stream processors considerably faster than the ones on the A10-7890K at their quickest: 1108MHz on the Bristol part versus 866MHz on the Godavari chip.

Combined with the architectural improvements of the Excavator CPU cores over the Steamroller cores in the A10-7890K, the A12-9800 might be as fast as or faster than the Godavari part in practice (though it doesn't have that K chip's unlocked multiplier for easy overclocking).

AMD wanted to make it clear which of its seventh-generation APUs are lower-TDP parts, as well, so it's bringing back the "E" suffix we've occasionally seen on other parts (the FX-8370E being the most prominent example). The A12-9800E, A10-9700E, and A6-9500E all slip into a 35W thermal envelope, at the expense of a couple hundred megahertz of clock speed for both their CPU cores and graphics processors.

AMD's internal benchmarks suggest that Bristol Ridge desktop parts are nipping at the heels of Intel's Skylake processors for regular desktop tasks, although the usual truckload of salt should probably apply to all of these claims. For example, the company says that in PCMark 8 Home Accelerated, an A12-9800 APU delivers performance equivalent to a Core i5-6500. It's worth noting that the Accelerated version of PCMark 8 uses OpenCL for some of its tasks, however, a configuration which might favor the AMD chip's IGP.

That powerful Radeon IGP does seem to give the A12-9800 a leg up in the 3DMark 11 Performance test. That benchmark runs at an undemanding 1280x720 resolution, and it's been superseded by the 3DMark Fire Strike and 3DMark Sky Diver benchmarks. Still, AMD says the A12-9800 doubles the performance of the Intel HD Graphics 530 IGP in the Core i5-6500 at 65W. The company also claims the 35W A12-9800E can deliver 88% better results in 3DMark 11 Performance versus the 35W Core i5-6500T.

Those results might make that top-end Bristol Ridge APU well-suited for basic gaming, but we'd be interested to see more user-experience-centric numbers like frame times (or even just average FPS) for these IGPs. 3DMark's index scores might be handy for broad comparisons, but they don't tell us anything about the actual gaming experience one might have with an AMD IGP.

For example, a $130-ish Radeon RX 460 4GB card like the one we recently reviewed turns in a 3DMark 11 Performance result of 9133 on one of our X99 testbeds, while the A12-9800's index score is actually just 3581 on its AM4 platform, according to AMD's materials. The RX 460 is what we would call a "solid" basic gaming experience, so we wouldn't expect to be blown back by the performance of the IGP on even this highest-end Bristol Ridge APU.

AMD also goes out of its way to highlight the performance-per-watt of these chips relative to the Intel competition, and it's here we need to raise a red flag. The company performed its efficiency calculations by subbing in a 91W Core i5-6600K for the 65W i5-6500 in comparison to the A12-9800, and that same Core i5-6500 for the 35W Core i5-6500T in comparison to its 35W A12-9800E. We won't lend these results any credibility except to say that when the goalposts are this mobile, you can make any claims you want. We have no idea why AMD made this switcheroo—it's about as subtle as dropping a hot coal in someone's pocket. 

Like Intel's recently-released Kaby Lake CPUs, Bristol Ridge offers hardware acceleration for the HEVC and VP9 video codecs. It's worth noting that these APUs can only perform hardware encoding and decoding of 4K content for HEVC, however—VP9 support is limited to 1080p content. Kaby Lake, on the other hand, can decode 4K VP9 content in hardware. Given that the next-generation codec wars still appear to be in full swing, Bristol's limited VP9 support may not be that important in the grand scheme of things.