Meet the Zhaoxin KX-U6780A: China’s First Homegrown x86 CPU
For the past few years, we’ve lightly covered the work of Zhaoxin, China’s first homegrown x86 CPU company. Zhaoxin is the result of a joint agreement between the Shanghai Municipal Government and the Taiwanese company VIA Technologies, which owns Centaur, which has an x86 license.
We’ve watched the release of updated Zhaoxin designs over the past few years, but the KX-6000 line is supposed to be something special — the first chip China ever claimed could compete with a (relatively) new Intel CPU, like the Intel Core i5-7400.
THG has gotten their hands on a reference motherboard implementing the high-end KX-U6780A and put the chip through its paces. Paul Alcorn has written an excellent article about the chip and what it means for China’s nascent CPU industry. China wants 100 percent of government offices to be buying homegrown hardware and software by 2022, and that may mean Zhaoxin’s x86 compatibility offers something unique that competing efforts based on other architectures (ARM, MIPS) don’t offer.
So, can the Zhaoxin KX-U6780A hang with budget AMD and Intel CPUs?
Short answer: No.
Long answer: No, but seeing where and how it falls down is interesting.
What We (Don’t) Know
Not much is known about either the integrated GPU or low-level CPU architecture. Zhaoxin did not distribute block diagrams or explain what interconnect design is used to connect the CPU with its integrated GPU. Automated tools were unable to pick up much in the way of useful information as far as GPU specs. It’s an x86 CPU with support for features like AVX (albeit poorly), VMX virtualization technology, and SSE 4.2, but the motherboard UEFI is rock-bottom minimal and there are no options for overclocking or changing DRAM speed.
Here’s what we do know: The KX-U6780A is an 8C/8T CPU built on TSMC’s 16nm process. It runs at 2.7GHz, with no turbo mode or L3 cache. Integrated GPU performance is very poor (19-20fps in DOTA 2 at lowest settings, compared with 105fps for an Intel UHD 630). Single-threaded CPU performance is also very poor.
THG has added a derived metric for the SMT-equipped CPUs, a “Multi-threaded per-core score.” This is meant to take the impact of Hyper-Threading into account and it shows the familiar pattern we expect: CPUs with SMT get a substantial kick upwards from it. Zhaoxin’s multi-threaded score is on par with a Pentium G5600, vastly off the results for a Core i5-7400. Its single-threaded performance is very poor; even the old A10-9700 (an Excavator-based, pre-Ryzen AMD CPU core) is more than 2x as fast in single-threaded workloads. While the KX-U6780A can beat the Athlon 3000G, that CPU is a 2C/4T chip.
This is the best single test result that the KX-U6780A turned in. In every other CPU test THG ran, the KX-U6780A loses by substantial margins to CPUs like the A10-9700, the Ryzen 3 3200G, and the Core i3-7100.
When equipped with an RTX 2080 Ti, the KX-U6780A typically performs at or slightly above the A10-9700. There is often a distinct falloff for these two cores compared with everything else:
Across the entire suite of games, I’d say the KX-U6780A is a bit faster than the A10-9700, but it’s behind virtually every other chip, virtually all of the time. Combined with the low CPU performance, this simply isn’t a very competitive core.
Still, it’s genuinely interesting to see another company come to market with an x86 architecture and, as Alcorn notes, Centaur (VIA’s CPU division) is reportedly working on a very impressive architecture that could be headed to Zhaoxin in the KX-7000 class of CPUs.
China’s ability to scale up its CPU business to compete with Intel and AMD is limited both by its fab technology and the difficulty of building a truly high-performance x86 CPU core. While the Zhaoxin KX-U6780A loses almost every test to budget Intel and AMD chips, the fact is, you have to show up to play before you can lose. China is signaling that it intends to compete more seriously for the PC processor market. Intel and AMD would be foolish if they didn’t pay attention.