Introduction

AMD Ryzen 5 8500G is the most affordable Socket AM5 processor that's available in the retail channel, making it the baseline for this platform, and the Zen 4 microarchitecture that it's based on. A 6-core processor with integrated graphics, the 8500G is intended to cover the widest demographic in the desktop PC market. Those who shop for processors around the $150-mark could otherwise end up getting either the current Core i3 SKU, or the cheapest Core i5 from the previous generation. PCs powered by the Ryzen 5 8500G are intended mainly for daily-driver productivity workloads with higher resolution displays, and a little richer non-gaming content, thanks to its feature-packed integrated graphics. The processor also debuts AMD's take on heterogeneous multicore (Hybrid).



The AMD Ryzen 5 8500G is technically an APU—a class of desktop processors by AMD that are supposed to feature oversized iGPUs that can take on mainstream gaming at lower resolutions; however, this is a significantly different kind of chip than the Ryzen 7 8700G and Ryzen 5 8600G, which really meet the definition of an APU. The 8500G is based on a physically smaller monolithic silicon that has no more than 6 CPU cores, and an iGPU 1/3rd the size of the one found in the 8700G. AMD codenamed this smaller die Phoenix 2, and built it on the same 4 nm process as Phoenix and Hawk Point, The idea behind Phoenix 2 is that it would be cheaper for AMD to sell a processor based on a 137 mm² monolithic silicon at the $160 price-point, compared to the "Raphael" chiplet-based processor, which entails the 5 nm CCD and a 6 nm cIOD, besides a complex package substrate.

The Ryzen 5 8500G packs a 6-core/12-thread CPU, but there's more to this. All six cores are based on the Zen 4 microarchitecture, but only two out of the six are full-sized Zen 4 cores, which can sustain the highest boost frequencies, while the other four are physically smaller Zen 4c cores. Zen 4c has identical IPC to Zen 4, as well as an identical instruction set architecture, it even features SMT, but has much lower voltage tolerances, which means both its base- and boost frequencies are lower, yielding a lower energy footprint. The Zen 4 and Zen 4c cores on Phoenix 2 share a unified core complex (CCX), and a 16 MB L3 cache, which means workloads can easily migrate between the two core types, and AMD can use simple preferred-core flagging to get the OS to prioritize work to the larger Zen 4 cores.

The integrated graphics solution on the Ryzen 5 8500G is the Radeon 740M. The Phoenix 2 silicon only features two RDNA 3 workgroup processors (WGPs), or 4 compute units (CU), worth 256 stream processors. This is a third the size of the iGPU powering the Phoenix silicon (6 WGPs), but more advanced than the potato iGPU AMD provides with the Ryzen 7000 "Raphael" processors, with just one WGP based on the older RDNA 2 architecture, which in AMD's own words, is just enough to "light up the screen and drive 2D productivity."

The two Zen 4 cores on the Ryzen 5 8500G come with a base frequency of 4.10 GHz, and boost up to 5.00 GHz. The four Zen 4c cores, on the other hand, have a 3.30 GHz base frequency, with a 3.70 GHz boost. Besides the tighter clock speed bands, the Zen 4c cores have an identical IPC, ISA, and L2 cache size to the regular Zen 4 cores, and the six cores share the chip's 16 MB L3 cache. The Radeon 740M iGPU comes with 4 compute units, and an engine clock of 2.80 GHz.

Unlike the Ryzen 5 8600G and Ryzen 7 8700G, the 8500G lacks an NPU, since the Phoenix 2 silicon physically lacks it. The memory interface is unchanged, with a dual-channel DDR5 memory interface with native support for DDR5-5200; however, the PCIe interface is further crippled. The chip has a total of 14 PCI Express Gen 4 lanes, from which four lanes are committed to the chipset bus, leaving just 10 lanes. Motherboards handle these by wiring out at least one M.2 NVMe slot with Gen 4 x4 wiring, and the PCI-Express x16 slot runs at electrical PCI-Express 4.0 x4, with the remaining 2 lanes being left for other CPU-attached devices.

AMD is pricing the Ryzen 5 8500G at $160 as of this writing, which puts it around $20 less than the Intel Core i5-14400F that lacks an iGPU. The retail package includes a cooling solution.

Architecture

AMD did not release any first-party die shots, renders, or block-diagrams of the Phoenix 2 silicon, but here is a public annotation of the die by BusAlexey on X, which is based on a public die-shot.


AMD Ryzen 5 8500G is based on the 4 nm Phoenix 2 silicon, which is physically smaller than the 4 nm Phoenix silicon driving the Ryzen 5 8600G and Ryzen 7 8700G. This chip comes with a die area of 137 mm², compared to the 178 mm² of Phoenix. AMD was able to make the chip smaller by limiting the CPU to just 6 cores, four of which are the 35% smaller Zen 4c cores, truncating the iGPU to just 4 CU (256 stream processors), removing the XDNA NPU, and reducing the PCI-Express root complex to just 14 Gen 4 lanes, compared to the 20 Gen 4 lanes on Phoenix.


The Zen 4c core is a spatially compacted version of Zen 4. No components are removed, and nothing is truncated. Even the L1 and L2 caches remain the same. What's changed is that AMD has used higher density libraries, and compacted the components at a silicon level. The resulting core offers the same exact IPC as Zen 4, it also supports SMT (two threads per core), and has an identical ISA (instruction sets), which means threads can seamlessly migrate between Zen 4 and Zen 4c cores without an ISA mismatch causing runtime errors.


The only trade-off with the Zen 4c engineering effort is performance (not IPC). Zen 4c has much lower voltage limits than Zen 4, which means it has a narrower clock speed band, and so any threads migrating from a Zen 4 core to a Zen 4c core will only experience lower performance, but not the lack of any hardware features. This common IPC and ISA means that the Zen 4 and Zen 4c cores sit in a common core complex (CCX), and share a 16 MB L3 cache, which should greatly benefit thread migration between the two core types.

AMD's approach to heterogeneous multicore is significantly different from that of Intel's. Because the P-core and E-core are significantly different to each other, with different IPC and ISA, Intel relies on a hardware scheduler called Thread Director, which ensures that the right kind of workload is allocated to the right core type. This is not the case with Phoenix 2. AMD is using UEFI CPPC preferred cores mechanism to mark the two Zen 4 cores as preferred cores to the OS, which ensures that most of the workload is sent to them, as they support the highest boost frequencies. Spillover workloads are allocated to the Zen 4c cores.

The platform I/O of the Phoenix 2 silicon is severely truncated from the regular Phoenix silicon powering the 8600G and 8700G. Its PCI-Express interface is limited to 14 lanes of PCI-Express 4.0, compared to the 20 lanes on Phoenix, and the lavish 28 Gen 5 lanes on the Raphael MCM. Socket AM5 motherboards handle the I/O of Phoenix 2 by wiring out just four Gen 4 lanes to the PCI-Express x16 PEG slot (now electrical PCI-Express 4.0 x4), and connecting just one of the two CPU-attached M.2 NVMe slots, which operates at Gen 4 x4. The chipset bus takes away another 4 lanes, leaving 2 lanes that are configurable as 20 Gbps USB 3.2, or to drive other onboard devices. The memory I/O is unchanged, you get two channels of DDR5.

The iGPU of Phoenix 2 is based on the latest RDNA 3 graphics architecture, and uses the latest versions of the Video CoreNext (VCN) media acceleration, as well as the latest Display CoreNext (DCN); but with just two workgroup processors (WGPs), or just 4 CUs, which work out to 256 stream processors, with 8 ROPs. The GPU ticks at 2.80 GHz. AMD has branded this iGPU the Radeon 740M. While it's still not the best fit for any gaming at 1080p, it should play some casual games at 720p, and you should get a fairly decent non-gaming experience, such as rich web rendering or high-resolution video. This should be sufficiently powerful as a HTPC iGPU, provided your motherboard has the right display connectors. The iGPU can decode H.265 4K video at 175 FPS. So there's plenty of heft for a 4K media experience.

The Zen 4 Microarchitecture

All cores in Ryzen 7000 series processors are of the same kind, what Intel would consider a performance-core, or P-core. AMD has worked on all three key stages of the CPU—the front-end, the execution, and the load/store. The front-end is the "mouth" of the CPU core, and prepares data and instructions for execution. Front-end improvements begin at the Branch Prediction unit, which can now predict 2 taken branches per clock-cycle, and comes with larger L1 and L2 branch-target buffers (BTBs). AMD had for the very first time introduced an op cache with Zen, improving it over time. AMD has increased the size of the op cache by around 68 percent. It can now handle 9 macro-ops per cycle. The micro-op queue dispatch rate to the execution stage is still 6.


The Execution Stage is the main number-crunching machinery, and broadly features two components for the kind of math workload being executed—Integer and Floating Point. The "Zen 4" execution stage features a 25% larger instruction retire queue, larger register files, and higher buffer queue-depths throughout the core.


With "Zen 4," AMD is introducing support for AVX-512, in a bid to increase the processor's AI inferencing performance. The company did this in a die-area efficient, and energy-efficient manner, with no impact on CPU core frequency. AVX-512 operations are executed on a dual-pumped 256-bit FPU, rather than building ground-up 512-bit FP machinery. VNNI and Bfloat16 instruction-sets are also added, which mean that "Zen 4" can handle pretty much all of the AVX-512 client-relevant workloads that competing Intel processors can.


The Load/Store unit is the part of the core that interfaces with the memory sub-system. The "Zen 4" core gets a 22 percent larger Load Queue, with improved data-port conflict-resolution. There's a 50% larger L2 data transition lookaside buffer. The cache-hierarchy of the Ryzen 7000 desktop processor is similar to that of Ryzen 5000, with a few key differences, besides bandwidth/latency improvements—the dedicated L2 cache has been doubled in size to 1 MB per core. The eight CPU cores on a CCD share a monolithic 32 MB L3 cache, with uniform access to each core.


These improvements contribute to a 13 percent IPC improvement over "Zen 3," AMD claims. The company provided a break-up of which components are contributing to the IPC uplift, and we see that close to two-thirds of it are coming from improvements to the front-end and load/store stages. Branch prediction improvements contribute a fifth of this uplift. Interestingly, the L2 cache contributes barely 1/10th of the IPC uplift, in the tested applications—we believe this increase is mostly relevant for server workloads where it should be able to make a difference. Intel's "Golden Cove" P-core comes with 1.25 MB L2 cache, and "Raptor Cove" features 2 MB. Despite the doubling in L2 cache sizes, the resulting increase in cache latency is very well contained (from 12 cycles on the 512 KB L2 of "Zen 3," to just 14 cycles on "Zen 4").


VBS (virtualization-based security) is the standard on new Windows 11 installs and gets activated automatically, unless you specifically disable it. Windows 11 Security Center already flags VBS not being enabled as a warning, similar to the Antivirus being disabled or outdated. AMD made several improvements to the Virtualization feature-set, to reduce its performance impact in a VBS-enabled client environment. This includes speculation control, dual AVIC to go with the physical dual-APIC, and TSC_AUX virtualization.

AMD X670E, B650E, and A620 Chipsets

AMD took a unique approach to chipsets with this generation. The top-tier chipset now comes in two flavors, X670E and X670. Both are identical in downstream I/O, but the X670E offers PCIe Gen 5 PEG besides CPU-attached Gen 5 NVMe; whereas the X670 only offers Gen 5 on the CPU-attached M.2 NVMe slot, but not PEG (which is Gen 4). A similar approach is taken when segregating the mid-tier B650E from the B650. The lack of Gen 5 PEG should significantly reduce motherboard costs, as designers would be saving on both Gen 5 re-drivers and the steep wiring requirements to avoid signal-corruption.

X670E is a two-chip chipset unlike the previous-gen X570. This was done to increase the downstream PCIe connectivity. The chipset now offers up to 12x PCIe Gen 4 and up to 8x PCIe Gen 3 downstream lanes (not counting the lanes from the CPU). This lets motherboard designers wire out three additional M.2 Gen 4 slots attached to the chipset, while the Gen 3 lanes handle low-bandwidth onboard devices. AMD adopted a wacky way to connect the two bridges that make up the chipset. There is an "upstream" chipset that's wired to the AM5 SoC over a PCI-Express 4.0 x4 connection; the second bridge is called "downstream" chipset, and is connected to four of the PCIe Gen 4 downstream lanes of the "upstream" chipset. The X670/E puts out up to two 20 Gbps USB 3.2, up to eight 10 Gbps USB 3.2, and twelve USB 2.0. The B650E and B650 look like more reasonable single-chip chipsets. They talk to the SoC over PCI-Express 4.0 x4, and wire out 8x PCIe Gen 4 downstream lanes, and up to 4x PCIe Gen 3 downstream lanes. You get half the number of USB SuperSpeed ports as the X670/E.


In early April 2023, AMD introduced the cost-effective A620 chipset. This makes sub-$100 motherboards possible, but is only intended for 65 W Ryzen 7000 processors. Some motherboard vendors may choose to provide support for 7000X and 7000X3D processors, but their processor power limits could be impacted. The A620 is similar in connectivity to the B650 (non-E), but you are limited to PCIe Gen 4 for both the PEG and CPU-attached NVMe slots, and the downstream PCIe connectivity from the chipset is limited to Gen 3. CPU overclocking is completely disabled, but you can overclock the memory and enable EXPO profiles just fine.

AMD EXPO Memory

With Ryzen 7000 series, AMD is introducing EXPO (extended profiles for overclocking); a feature that's identical in concept to Intel XMP. AMD EXPO-certified DDR5 modules come with an easy method of applying the advertised memory speeds and timings—you simply select a toggle in the opening screen of your motherboard's UEFI BIOS program. EXPO differs from XMP in that it includes fine settings that are unique to the AMD architecture, and it's also an open standard. Until now, XMP modules installed on AMD systems relied either on painstaking manual overclocking, or use of DOCP, a feature that attempts to translate the settings in the XMP profile to "nearest neighbors" of AMD-compatible settings. This was sub-optimal. EXPO is royalty-free compared to XMP, so any memory manufacturer can implement it for free. Ryzen 7000 can run any PC-DDR5 memory in the market, including XMP-certified kits.

Socket AM5

Here are a few pictures of Socket AM5, the star-attraction with this platform. This is a land-grid array (LGA) socket with 1,718 pins.


As with every LGA socket, the pins are on the motherboard, whereas the processor package has contacts that interface with those pins, while a retention brace holds the package in place with a locking lever. Installing a processor on AM5 is similar to doing so on any of the dozens of Intel LGA sockets.


On Socket AM4, removing the four mounting screws resulted in the backplate falling off, which meant you needed three hands when installing a cooler, and several vendors also bundled their own backplates. On Socket AM5 the backplate isn't designed to be removed, which makes cooler installation MUCH easier.


The caps for the socket are not identical to the Intel LGA sockets, so you can't reuse them.

DDR5 Memory

Much like the AMD Ryzen 7000 series, the new Ryzen 8000G series APUs lack backwards compatibility with DDR4 memory. So you'll not come across motherboards with DDR4 slots, and will need to buy new memory. DDR5 generationally doubles the data transfer-rates over DDR4, operates at lower voltages, comes with intrinsic ECC which Ryzen 7000 and 8000 series support at a silicon-level, and is optimized for parallelism, since each 80-bit memory channel contains two 40-bit sub-channels (independent paths to the memory controller).

Unboxing and Photography

The Ryzen 5 8500G ships in a package that looks similar in box design to the Ryzen 5 7000 series, particularly the Ryzen 5 7600. Unlike the 8600G and 8700G, the box doesn't scream support for Ryzen AI, since the chip lacks an NPU.


The Ryzen 5 8500G looks like every other Socket AM5 processor, except there are no visible SMDs in the grooves of the IHS. The Phoenix 2 die is tiny, and has simple electrical requirements.


The package includes an AMD Wraith Stealth fan-heatsink. This is designed for processors with 65 W TDP.


The AM5 socket retention brace only applies pressure along the two side protrusions of the IHS. Intel sockets have it the same way.

Test Setup

• All applications, games, and processors are tested with the drivers and hardware listed below—no performance results were recycled between test systems.
• All games and applications are tested using the same version.
• All games are set to their highest quality setting unless indicated otherwise.