Introduction

AMD today released its Ryzen 2000 family of processors with integrated AMD Radeon Vega graphics. 2017 was probably the best year in a decade for AMD's client CPU business. The company's Ryzen family of desktop processors, powered by its latest "Zen" microarchitecture, is surprisingly fast and stirred up competition enough to force Intel to increase CPU core-counts to catch up. AMD now has a reasonably competitive processor for every price point from $120 to $999, including HEDT processors, to compete with Intel's Core X family. The trouble is that none of these chips come with integrated graphics, a department in which AMD has traditionally outclassed Intel eversince it started making APUs.

Backed by its Radeon GPU expertise, strong integrated graphics had been the only selling point of AMD's client CPU lineup until good CPU performance from "Zen" came along. The company took the logical next step of combining its latest CPU microarchitecture with its latest GPU architecture, "Vega," to create its new 14 nm "Raven Ridge" silicon. Why "Vega" and not "Polaris," you ask? Because "Vega" has AMD's latest video decode acceleration engine and 6th generation Graphics CoreNext compute units (you'd want the most IPC from your limited SIMD resources). The company debuted this chip in the mobile space in late-2017 and is now launching it in the desktop segment with two SKUs - the Ryzen 3 2200G and Ryzen 5 2400G, which we're reviewing today.



Both models combine a quad-core "Zen" CPU with a "Vega" based integrated graphics core (iGPU), a dual-channel DDR4 integrated memory controller, and a platform I/O interface. Differentiating the two SKUs, the Ryzen 5 2400G gets SMT (AMD's equivalent of HyperThreading) and more iGPU stream processors, besides higher CPU and iGPU clock speeds. AMD surprised us with a larger-than-expected iGPU, and a smaller-than-expected CPU. The iGPU is endowed with up to 11 "Vega" NGCUs (next-generation compute units), which translate into 704 stream processors and 44 TMUs. On the Ryzen 5 2400G, you get all of them, and hence, the resulting iGPU is labeled "Radeon Vega 11." The Ryzen 3 2200G gets just 8 NGCUs, so 512 stream processors, and the "Radeon Vega 8" iGPU model. The CPU component is smaller than expected. By this generation, we expected AMD to increase core-counts on its APUs from the traditional quad-core setups. It's still quad-core, but the L3 cache is just 4 MB, half that of quad-core SKUs based on the iGPU-devoid "Summit Ridge" silicon, such as the Ryzen 3 1200.

Both the Ryzen 3 2200G and Ryzen 4 2400G work on existing socket AM4 motherboards based on AMD 300-series chipset, provided they have the latest BIOS. You can finally plug your monitor to the display connectors of your motherboard and not end up with a blank screen. AMD recommends the A320 and B350 chipsets as the ideal companions for these two chips, although the high-end X370 chipset will very much support it. There is, however, a big catch. You will not be able to use the second PCI-Express 3.0 x16 slot on your X370 motherboard. This is because the integrated PCI-Express root complex of "Raven Ridge" has just 8 PCI-Express 3.0 lanes for PCI-Express Graphics (PEG), 4 lanes toward the chipset-bus and 4 lanes toward an M.2 PCIe slot. Any graphics cards you may choose to install on a machine powered by these chips will be limited to PCI-Express 3.0 x8 bandwidth no matter the chipset or motherboard.

AMD is pricing the Ryzen 3 2200G and Ryzen 5 2400G rather conservatively. The 2200G is priced at US$99, and the 2400G at US$169. AMD is hedging its bets on the entry-level crowd that combines a $70-ish Pentium/Celeron processor with an entry-level graphics card, such as the GeForce GT 1300 or the Radeon RX 550. This chip will prove particularly appealing to gaming iCafe operators in emerging markets or those who want a desktop with a super high-resolution (think 4K or 5K) monitor, who don't intend to game. The DIY HTPC crowd will also find these chips appealing for their feature-rich iGPUs that have sufficient muscle and DRM features for smooth 4K HEVC content playback with a degree of future-proofing.

A Closer Look

The Ryzen 5 2400G comes in a fairly big cubical box characteristic of the Ryzen 5 series. You can tell that it comes with integrated graphics by looking at silver bands on the box with that catchy AMD Vega logo.


AMD is including a Wraith Stealth cooling solution with the 2400G and 2200G. This is the smallest stock cooling solution by AMD for this generation (after Wraith Max and Wraith Spire), but AMD feels it is sufficient for the 65W TDP of these chips. The design focus is still on low noise.


The Ryzen 5 2400G package looks like just any other Ryzen socket AM4 processor. You can install it on any AM4 motherboard if its BIOS is up to date.


AMD continues to use the AM4 socket, which means all existing Ryzen motherboards will be compatible with Ryzen G (after a BIOS update). The company also plans to stick to AM4 for the rest of this decade, so there's a pretty long upgrade-path ahead for this platform.

AM4 still has a rectangular cooler-mount-hole layout (as opposed to the square ones on Intel LGA platforms). AMD should have switched to a square layout to make it easier to orient tower-type coolers to blow hot air out the rear of the case. Current AM4-ready tower coolers have elaborate retention module kits that let you do so. Most popular cooler vendors are either selling or giving away AM4 retention modules for free. You often also have to remove the plastic retention module motherboards ship with to install certain kinds of coolers.

Architecture

At the heart of the Ryzen 5 2400G is the new 14 nm "Raven Ridge" silicon. 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 "Summit Ridge" silicon AMD launched the "Zen" CPU microarchitecture with, "Raven Ridge" has just four "Zen" CPU cores, but a rather large iGPU based on the "Vega" graphics architecture.

Before its debut late-2017 in its mobile avatar, we were expecting AMD to increase CPU core-counts for its first "Zen" based APU. Unfortunately, that isn't to be, but the quad-core CPU you do get has SMT (multi-threading) enabled on the Ryzen 5 2400G. Why four cores? This is partially because of the way AMD designed multi-core chips using its "Zen" micro-architecture.

AMD decided that four "Zen" CPU cores group better for its product managers to carve out SKUs with when designing the CCX (CPU complex). Each CCX has four CPU cores, each with dedicated L2 caches and a shared L3 cache. "Summit Ridge" has two CCX units running in a 2+2 configuration; while "Raven Ridge" combines one CCX (4+0) with the Vega 11 iGPU.



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. This is also why you can't directly compare CPU performance of the Ryzen 5 2400G clock-for-clock with the Ryzen 3 1200 "Summit Ridge," which has two cores enabled per CCX and 4 MB of L3 cache per CCX. It's the "4+0 vs. 2+2" face-off we wanted, though the 4+0 combination doesn't have the same amount of cache as 2+2. Each of the four cores still has 512 KB of dedicated L2 cache. The 2400G features SMT, while the 2200G lacks it.

Another major difference between "Summit 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 chipset motherboards won't work, and whatever graphics card you install on the first slot will run at PCI-Express 3.0 x8 (half bandwidth). This design choice is bewildering due to the potential PR drama. The actual performance lost from PCIe x8 3.0 vs. PCIe x16 3.0 is minimal. 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 up to 704 stream processors spread across 11 compute units, 44 TMUs, and 16 ROPs. It features DirectX 12 and Vulkan support and can conduct hardware-accelerated decoding of HEVC/x265/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 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 that 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.



AMD has three chipsets for Ryzen - the X370 for high-end desktops, which supports proprietary multi-GPU technologies, such as NVIDIA SLI, the mid-tier B350 chipset with a slimmer connectivity feature set, and the entry-level A320 chipset for low-cost desktops (which lacks multiplier overclocking support). NVIDIA SLI will not work on X370 chipset motherboards if paired with "Raven Ridge" processors, which is due to the PCIe lane limitation of the processor.