AMD Radeon R5 M420 vs AMD Radeon R8 M445DX Comparison

The AMD Radeon R8 M445DX and AMD Radeon R5 M420 are both end-of-life mobile graphics solutions from the same generation, but the benchmark data reveals a clear performance hierarchy. The R8 M445DX holds a decisive lead in the single recorded compute test, placing it in a higher performance tier relative to the rest of the database. The following analysis breaks down the measured results, the architectural differences that explain them, and the specific use cases where each chip holds an advantage.

Head-to-Head Benchmarks

The database contains one direct comparison between these two GPUs: the Geekbench OpenCL test. In this single benchmark, the AMD Radeon R8 M445DX scored 4727, while the AMD Radeon R5 M420 scored 3956. This represents a delta of 19.5% in favor of the R8 M445DX, a substantial margin that indicates a meaningful difference in raw compute throughput.

Looking at the percentile rankings, the R8 M445DX sits at the 27th percentile of all GPUs in the database, while the R5 M420 sits at the 23rd percentile. While both are in the lower half of the performance spectrum, the R8 M445DX is noticeably closer to the mid-range. The R5 M420's nearest rivals include the NVIDIA GeForce 830M (avg score 3957, delta 0%), the NVIDIA GeForce GT 745M (avg score 3953, delta 0.1%), and the NVIDIA Quadro K2000 (avg score 3964, delta -0.2%). These are extremely tight groupings, with the R5 M420 essentially trading blows within a fraction of a percent of these older discrete parts.

The R8 M445DX, by contrast, competes in a slightly higher bracket. Its nearest rivals include the AMD Radeon R5 M335 (avg score 4752, delta -0.5%), the NVIDIA Quadro P400 (avg score 4684, delta 0.9%), and the AMD Radeon R5 M255 (avg score 4788, delta -1.3%). Interestingly, the R8 M445DX also sits within 1.3% of the NVIDIA GeForce RTX 3080 12 GB (avg score 4791) in this specific OpenCL workload, though that is a reflection of the test's nature rather than any practical equivalence. The data shows that the R8 M445DX is not just faster than the R5 M420, it is positioned in a different competitive class, one that includes more capable discrete mobile GPUs.

The 19.5% delta between the two AMD parts is significant because the underlying shading unit count and texture unit count are identical. The performance gap must therefore come from other factors, primarily clock speeds and memory configuration, which are examined in the specification and architecture sections.

FAQ

Q: Which GPU has the higher benchmark score?

A: The AMD Radeon R8 M445DX scores 4727 in Geekbench OpenCL, compared to 3956 for the AMD Radeon R5 M420. The R8 M445DX is 19.5% faster in this test.

Q: How do these GPUs compare to their nearest competitors?

A: The R8 M445DX is within 0.9% of the NVIDIA Quadro P400 (4684) and 0.5% of the AMD Radeon R5 M335 (4752). The R5 M420 is essentially tied with the NVIDIA GeForce 830M (3957) and the NVIDIA GeForce GT 745M (3953).

Q: Do both GPUs have the same number of shading units?

A: Yes, both the AMD Radeon R8 M445DX and the AMD Radeon R5 M420 feature 320 shading units and 20 texture mapping units. They also both have 8 raster operation units.

Q: What is the memory configuration of the R5 M420?

A: The AMD Radeon R5 M420 uses 4 GB of DDR3 memory on a 64-bit bus, delivering 16.00 GB/s of bandwidth. The memory clock is 1000 MHz, which translates to 2 Gbps effective.

Q: What is the memory configuration of the R8 M445DX?

A: The AMD Radeon R8 M445DX uses system shared memory, meaning its memory size, type, and bus width are all system dependent. The bandwidth is also system dependent.

Q: What is the performance percentile for each GPU?

A: The R8 M445DX is in the 27th percentile of all GPUs in the database, while the R5 M420 is in the 23rd percentile.

Where Each One Wins

The AMD Radeon R8 M445DX wins the only recorded benchmark, the Geekbench OpenCL test, with a 19.5% advantage. This makes it the clear choice for any workload that is sensitive to raw compute throughput, such as general-purpose GPU computing tasks, OpenCL-accelerated applications, or any form of content creation that can leverage the GPU. Its higher boost clock and superior pixel and texture rates support this: the R8 M445DX achieves 8.168 GPixel/s and 20.42 GTexel/s, compared to 6.800 GPixel/s and 17.00 GTexel/s for the R5 M420. These are measurable wins in fill-rate limited scenarios.

The AMD Radeon R5 M420 does not win any benchmark in the database. However, its use case is defined by its memory configuration. It has a dedicated 4 GB of DDR3 memory with a fixed 64-bit bus, which means it does not depend on the host system's RAM. In a system with slower or shared memory, the R5 M420 could offer more consistent memory performance, since it is not competing with the CPU for bandwidth. This makes it a more predictable option for basic tasks like video playback or light gaming, where the dedicated frame buffer can prevent stutter caused by memory contention.

The R8 M445DX, with its system shared memory, is entirely dependent on the host laptop's memory subsystem. In a system with fast dual-channel memory, the R8 M445DX could potentially exceed the performance of the R5 M420 by even more than the 19.5% benchmark delta. Conversely, in a system with slow or single-channel memory, the advantage could shrink. The benchmark score recorded in the database reflects a specific system configuration, so the real-world performance of the R8 M445DX will vary more than the R5 M420's.

Specification Differences

The two GPUs differ in several key clock and memory specifications. The AMD Radeon R8 M445DX has a base clock of 780 MHz and a boost clock of 1021 MHz. The AMD Radeon R5 M420 has the same base clock of 780 MHz but a lower boost clock of 850 MHz. This 171 MHz difference in boost clock is a primary driver of the performance gap.

The memory subsystems are completely different. The R8 M445DX uses system shared memory, with the size, type, bus width, and bandwidth all listed as system dependent. The R5 M420 has a fixed configuration: 4 GB of DDR3 memory on a 64-bit bus, with a bandwidth of 16.00 GB/s and a memory clock of 1000 MHz (2 Gbps effective).

The floating-point performance reflects the clock differences. The R8 M445DX delivers 653.4 GFLOPS of FP32 compute, while the R5 M420 delivers 544.0 GFLOPS. The R8 M445DX also supports FP16 at a 1:1 ratio with FP32, both at 653.4 GFLOPS, while the R5 M420 has no recorded FP16 capability.

The bus interface also differs. The R8 M445DX is listed as an IGP (integrated graphics processor) with no separate bus interface, while the R5 M420 uses a PCIe 3.0 x8 interface. This suggests the R8 M445DX is designed to be a more tightly integrated solution, while the R5 M420 is a more traditional discrete chip that connects via the PCIe bus.

Architecture Differences

The AMD Radeon R8 M445DX is built on the GCN 3.0 architecture, while the AMD Radeon R5 M420 uses the older GCN 1.0 architecture. This is a significant generational difference. GCN 3.0 includes architectural refinements over GCN 1.0, particularly in compute efficiency and feature support.

The chip itself differs. The R8 M445DX uses the "Meso" chip, while the R5 M420 uses the "Jet" chip. The Meso chip is substantially larger, with 1,550 million transistors on a 125 mm² die. The Jet chip has 690 million transistors on a 56 mm² die. Both are manufactured on a 28 nm process at TSMC, and the transistor density is nearly identical: 12.4M per mm² for the R8 M445DX, and 12.3M per mm² for the R5 M420. The difference in die size is the primary reason for the performance gap, as the larger chip allows for the same number of shading units but with more supporting logic and higher clock potential.

The DirectX support differs. The R8 M445DX supports DirectX 12 (12_0), while the R5 M420 supports DirectX 12 (11_1). This means the R8 M445DX has access to a newer feature set within the DirectX 12 API. Both support OpenGL 4.6 and Vulkan 1.2.170.

The generation labels also differ. The R8 M445DX is from the "Gem System Hybrid (Rx M400)" generation, while the R5 M420 is from the "Gem System (R5 M400)" generation. The R5 M420 lists its predecessor as "Solar System" and its successor as "Polaris Mobile," while the R8 M445DX lists no predecessor or successor in the database.

The Verdict

The AMD Radeon R8 M445DX is the objectively faster GPU in the database's measurements. Its 19.5% benchmark advantage over the R5 M420 is backed by a higher boost clock, more modern GCN 3.0 architecture, and a larger, more powerful chip with over twice the transistor count. It also carries a higher percentile ranking (27th vs 23rd), placing it in a more competitive performance tier. For any user prioritizing raw compute performance, OpenCL acceleration, or higher fill rates, the R8 M445DX is the clear choice.

The AMD Radeon R5 M420, however, is not without its own rationale. Its dedicated 4 GB of DDR3 memory is a fixed resource that does not depend on the host system's RAM. This makes it a more predictable option for systems where the shared memory of the R8 M445DX might be a bottleneck. The R5 M420 also uses less silicon, with a 56 mm² die compared to 125 mm², which could have implications for power consumption and heat generation, though the database does not record TDP values for either GPU.

For a user with a laptop that has fast, dual-channel system memory, the R8 M445DX is the superior choice. Its performance is not only ahead in the recorded benchmark, but its system shared memory architecture has the potential to exceed recorded results if paired with a high-bandwidth memory subsystem. For a user with a laptop that has limited or slower system memory, the R5 M420's dedicated frame buffer might provide more consistent, if lower, performance.

In summary, the data shows a clear performance hierarchy. The R8 M445DX wins the compute race, while the R5 M420 offers a fixed memory footprint that could be preferable in specific system configurations. The choice ultimately comes down to whether the user prioritizes peak performance, which points to the R8 M445DX, or memory independence, which points to the R5 M420.