AMD Athlon 200GE 3.2 GHz Review 57

AMD Athlon 200GE 3.2 GHz Review

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Architecture

The Athlon 200GE is built on the same 14 nm "Raven Ridge" silicon as the much pricier Ryzen 2000G APUs. This chip is a full-fledged SoC which combines a CPU, an integrated GPU (iGPU), a dual-channel DDR4 memory controller, platform I/O, and integrated southbridge. Unlike the 8-core "Pinnacle Ridge" silicon, "Raven Ridge" has just four "Zen" CPU cores, of which two are disabled in this chip, and a rather large iGPU based on the "Vega" graphics architecture, of which only 3 out of 11 Vega next-gen compute units (NGCUs) are enabled.

Unlike the Ryzen 3 2200G, the Athlon 200GE features SMT, making its CPU component 2-core/4-thread. SMT is necessitated by an increasing number of games refusing to work with less than four logical processors. This is also why Intel added HyperThreading to even its Pentium parts. The addition of SMT also allows AMD to improve the CPU's competitiveness to the Celeron G4900 series processors based on the "Coffee Lake" silicon, which lack HTT. The CPU is clocked at 3.20 GHz and lacks some of the AMD SmartMI features its Ryzen-branded siblings have, such as Precision Boost.



The "Raven Ridge" silicon combines one quad-core "Zen" compute complex (CCX) and a large iGPU with up to 11 NGCUs. It's important to note that the CCX of "Raven Ridge" is slightly different from the one found on "Summit Ridge" because its shared L3 cache is halved to just 4 MB. Interestingly, AMD decided to give the Athlon 200GE the full amount of L3 cache present on this chip. Each of the two cores has 512 KB of dedicated L2 cache.

Another major difference between "Pinnacle Ridge" and "Raven Ridge" is the latter's smaller PCI-Express (PCIe) root complex. While "Summit Ridge" features 16 PCIe Gen 3.0 lanes toward PEG (PCI-Express Graphics) in addition to 4 lanes allocated to the chipset-bus and another 4 lanes driving an M.2 NVMe slot, "Raven Ridge" puts out just 8 lanes toward PEG, besides 4 lanes as chipset-bus and 4 lanes for the M.2 NVMe slot. What this means is that the second PCI-Express 3.0 x16 slot on X370 and X470 chipset motherboards won't work, and whatever graphics card you install in the first slot will run at PCI-Express 3.0 x8 (half bandwidth). This design choice is bewildering due to the potential perception drama. The actual performance lost from PCIe x8 3.0 vs. PCIe x16 3.0 is minimal unless you're using some of the newer NVIDIA Turing GPUs, which makes no sense given the low price point of the Athlon 200GE. The Vega integrated graphics is connected to the CPU using Infinity Fabric.

The iGPU implements AMD's latest "Vega" architecture with separate regions on the "Raven Ridge" silicon for the iGPU's key components and the display controllers with multimedia processing. It is endowed with 192 stream processors spread across 3 compute units, 12 TMUs, and 4 ROPs. It features DirectX 12 and Vulkan support and can conduct hardware-accelerated decoding of HEVC/H.265/VP10. It has the necessary DRM features to enable playback of Netflix 4K-HDR and other emerging high-resolution content services. Its display controllers support 4K Ultra HD and 5K displays through DisplayPort 1.4. The iGPU is hence branded "Radeon Vega 3."

The Zen Architecture

The oldest reports about AMD working on the "Zen" architecture date back to 2012, when AMD re-hired CPU core designer Jim Keller credited with the original winning K8 and K9 architecture designs to work on a new core architecture to succeed "Bulldozer." AMD continued to invest in the "Bulldozer" IP in the form of incremental core updates, hoping that trends in the software industry towards parallelization would improve, giving it a big break in price/performance. Those trends, in the form of DirectX 12 and Vulkan 3D APIs being multi-core friendly, came in a tad late (towards late 2016). Four years of work by a team dedicated to its development, led by Jim Keller, resulted in the "Zen" core.



At the heart of the "Zen" core are two very important innovations - a very "intelligent" branch-prediction system that uses neural nets (yes, of the same kind as power deep-learning machinery) to predict branches in code and load the most appropriate instructions and allocation of core resources and a 1.5X increase in issue width and execution resources, besides a 1.75X increase in the instruction scheduler window. Intel had been beating AMD in core performance and efficiency in exactly these two areas, and AMD finally addressed it instead of throwing in many more hardware resources without addressing the branch-prediction issues. "Zen" also features an up-to-date ISA instruction set including AVX2, FMA3, and SHA.



Interestingly, AMD talks about refinements to the micro-architecture itself in its Ryzen 2000G press deck for these processors, which speak of improvements to the various SenseMI components.

The AM4 Platform

What sets "Summit Ridge" apart from Intel dies, such as "Kaby Lake," is that it is a full-fledged SoC (system-on-chip). It integrates both the northbridge and southbridge. In addition to memory and PCIe, socket AM4 processors also put out USB 3.0 and two SATA 6 Gb/s ports. The platform still has something called a "chipset," but it only serves to increase connectivity options, such as adding more SATA ports, USB 3.1 ports, and a few more general-purpose PCIe lanes. On Intel's platforms, the PCH (platform controller hub) serves the functions of the southbridge, while the northbridge is fully integrated with the processor.

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