AMD's Next-Generation APU Hits Notebooks
Six months ago, AMD introduced its Kaveri APU design to the desktop market. It represented a lot of firsts for the company. For instance, it was the first processor to feature what AMD calls a truly Heterogeneous System Architecture (HSA). Its x86 execution cores are the first to leverage the Steamroller architecture, replacing the Piledriver design leveraged in both Trinity and Richland. Kaveri is also the first desktop APU armed with AMD's Graphics Core Next (GCN) architecture, featuring many of the same building blocks at the heart of today's discrete Radeon graphics cards, offering TrueAudio functionality and support for AMD's Mantle graphics API.
On paper, and in practice, Kaveri is a compelling mainstream, budget-oriented SoC. You can read more about it in our launch coverage: AMD A10-7850K And A8-7600: Kaveri Gives Us A Taste Of HSA.
Unfortunately, the APU's life in the desktop space isn't easy. Kaveri is intended to operate within a broad range, from 15 to 95 W. AMD has already talked about sweet spots inside of that thermal envelope; right from the start, company representatives said this design does its best work at TDPs under 45 watts.
We also know that Kaveri's 28 nm SHP bulk silicon process optimizes density at the expense of higher clock rates, which could be another reason the mobile version proves more capable than anything AMD could enable on the desktop.
Indeed, when it comes to the desktop, the 45 W A8-7600 (an APU that we reviewed in January, but is still not available to purchase, by the way), serves up performance results that look impressive compared to the 95 W A10-7850K. In other words, you get relatively little extra in the benchmarks for the 50 W-higher power ceiling. In fact, in many cases, the Kaveri-based A10-7850K barely improves on the previous-generation A10-6800K, which offers more overclocking headroom thanks to its 32 nm SOI process.
Yes, Kaveri's Steamroller-based cores do get more work done per clock cycle than Piledriver. However, the architecture's advantages are largely masked by lower clock rates at comparable power levels. When the playing field is normalized by battery power, though, AMD says its modern APU design is at its best.
And so we now have fairly aggressive expectations, shaped by AMD's triumphant marketing message. At the end of the day, though, engineering has to live up to the PR team's promises. It's time to determine whether practice lives up to theory.