Zen 2’s launch was a defining moment for AMD. For the first time in many, many years, AMD’s single thread performance could go head to head with Intel’s best. Zen 2 also started a trend where AMD brought up to 16 cores to desktop CPUs, giving consumers very strong multithreaded performance without having to buy HEDT platforms.
But Zen 2 was also flexible and did a very good job of scaling down to lower power targets. That was especially true when Zen 2 cores were implemented in more power efficient monolithic dies. Possibly because of that, the Zen 2 architecture went on to serve in new products even after Zen 3’s late 2020 launch. In 2021, Lucienne products like the Ryzen 7 5700U used Zen 2 cores in an updated platform. Mendocino launched in 2022 to target low power laptops, with Zen 2 cores ported to TSMC’s 6 nm process. Van Gogh is yet another example. It’s a rather unique product that combines RDNA 2 with four Zen 2 cores on TSMC’s 7 nm process.
Steam Deck with back cover removed
Unlike Lucienne and Medocino, Van Gogh isn’t a general purpose laptop chip. It only shows up in the Steam Deck, an ultraportable gaming console with a form factor that’s vaguely comparable to Nintendo’s Switch. Of course, the Steam Deck is meant to run PC games, which can be significantly more demanding. Unlike its Zen 2 cousins, the Van Gogh chip in the Steam Deck didn’t get a proper name. It instead reports itself as “AMD Custom APU 0405”.
Configuration
The Steam Deck has 16 GB of LPDDR5: two Samsung chips with 8 GB of capacity each. They’re arranged in four 32-bit channels and run at 5500 MT/s, which should give 88 GB/s of theoretical bandwidth. The motherboard is called “Valve Jupiter”. It connects the APU to an x4 M.2 slot, and provides x1 PCIe links to a micro-sd card controller and a Realtek 8822CE WiFI card.
Photo of the VRM configuration with a Nikon D850 and 105mm macro. Enjoy the high resolution
Power to the APU is provided by three VRM stages, controlled by a MP2845. Two of the stages are marked 8690 2823 B, while a third is marked 8690 3000 C. The VRM is possibly split into a two-stage component and a separate single-stage one. Therefore, the VRM is rather weak, but that’s not a huge deal considering the APU appears to be capped at 16 W. That power budget is flexibly allocated between the CPU and GPU. For example, a GPU-bound sequence could see the GPU pulling over 10 W, while the CPU side gets squished below base clock and draws 2-3 W. The opposite applies for a CPU-only workload.
Checking the after-action report in GHPC. This activity is mostly GPU bound, and sees the power budget dominated by the GPU running full-tilt at 1.6 GHz. In contrast, the CPU gets squished into a tiny power budget and runs at cell-phone like clocks.
This sort of flexible power allocation can work well when a game is primarily CPU bound or GPU bound. But it does leave performance on the table if you’re trying to use both the CPU and GPU together to maximize compute throughput. Typically, you see that happen with compute applications, like renderers and photo processing applications. The Steam Deck doesn’t primarily target that, so it should be fine unless a game pegs both the CPU and GPU at the same time.
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