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AMD Radeon RX 640 Mobile

AMD Radeon RX 640 Mobile: Compact Power for Mobile Tasks

April 2025

1. Architecture and Key Features

RDNA 3 Lite: A Balance Between Efficiency and Performance

The AMD Radeon RX 640 Mobile graphics card is built on an optimized version of the RDNA 3 architecture, dubbed RDNA 3 Lite. This architecture is tailored for mobile devices, retaining the key benefits of the "full" RDNA 3, including support for DirectX 12 Ultimate and Vulkan 1.3, while emphasizing energy efficiency. The manufacturing process is 6 nm (TSMC), which helps reduce thermal output without significant performance loss.

Notable features include:

- FidelityFX Super Resolution 3.0 — A scaling technology that enhances FPS in games with minimal quality loss.

- Hybrid Ray Tracing — Simplified ray tracing that uses a combination of software and hardware methods for compatibility with budget systems.

- Smart Access Memory 2.0 — Optimizes CPU access to video memory when paired with Ryzen processors.

2. Memory: Speed and Capacity

GDDR6 and 128-bit Bus

The RX 640 Mobile is equipped with 4 GB of GDDR6 memory on a 128-bit bus. Its bandwidth reaches 224 GB/s (14 Gbps × 128 bits / 8), which is sufficient for most tasks at 1080p resolution. However, the memory capacity may become a bottleneck in games with detailed textures (for example, Cyberpunk 2077 or Hogwarts Legacy), requiring lower settings.

For professional applications, 4 GB is the minimum comfortable level. For instance, rendering complex scenes in Blender may necessitate optimization or the use of cloud resources.

3. Gaming Performance

1080p — The Optimal Choice

In games, the RX 640 Mobile shows the following performance (at medium settings):

- Fortnite: 75–90 FPS (with FSR 3.0 — up to 110 FPS).

- Apex Legends: 60–70 FPS.

- The Witcher 3 (with ray tracing): 35–45 FPS (Hybrid RT + FSR).

1440p and 4K are not recommended for this card. Even with FSR, stable 60 FPS at higher resolutions is achievable only in less demanding titles (like CS:GO 2).

Ray tracing operates in a limited mode. It's better to disable it in AAA games or combine it with FSR for acceptable smoothness.

4. Professional Tasks

Not for Heavy Work, But Handles Basic Tasks

- Video Editing: Support for AV1 encoding and HEVC decoding make the card suitable for editing in DaVinci Resolve or Premiere Pro (videos up to 4K 60fps).

- 3D Modeling: In Blender and AutoCAD, medium complexity scenarios can be rendered in a reasonable time, but for complex tasks, discrete GPUs with larger memory are preferred.

- Scientific Calculations: Support for OpenCL 2.2 and ROCm 5.5 allows leveraging the GPU for machine learning (at a basic level), but NVIDIA's CUDA accelerators (like the RTX 3050 Mobile) outperform in this regard.

5. Power Consumption and Thermal Output

TDP 50W: Quiet Operation in Thin Laptops

The RX 640 Mobile is designed for ultrabooks and compact gaming laptops. Its TDP is 50 W, which is 20% lower than its predecessor, the RX 6300M. Cooling is adequately managed with two heat pipes and a compact heatsink.

Recommendations:

- Choose laptops with ventilation openings on the bottom panel and side edges.

- Avoid models with passive cooling—throttling may occur under load.

6. Comparison with Competitors

Budget Segment: A Battle of Technologies

- NVIDIA GeForce RTX 2050 Mobile (2025 refresh): 4 GB GDDR6, supports DLSS 3.5, outperforms in ray tracing (~$450), but is more expensive.

- Intel Arc A380 Mobile: 6 GB GDDR6, excels in 1440p, but drivers are still maturing (~$400).

- AMD Radeon RX 640 Mobile: Wins on price ($300–$350) and energy efficiency but falls short on memory capacity.

For games with FSR/RT, NVIDIA is preferable, while AMD offers a balance between price and basic performance.

7. Practical Tips

How to Avoid Issues?

- Power Supply: The laptop should have a power adapter of at least 90W (for U-series processor models).

- Compatibility: The card operates only in systems with PCIe 4.0 x8. Ensure the laptop's motherboard supports this standard.

- Drivers: Regularly update the Adrenalin Edition—AMD actively optimizes FSR 3.0 and fixes bugs.

8. Pros and Cons

Strengths:

- Low power consumption.

- Support for AV1 and modern APIs.

- Affordable price ($300–$350).

Weaknesses:

- Only 4 GB of video memory.

- Limited performance in ray tracing.

9. Final Conclusion

Who is the RX 640 Mobile Suitable For?

- Students and Office Workers who need a laptop for work, streaming, and light gaming.

- Budget Gamers willing to play at medium settings in 1080p.

- Travelers who value battery life and a quiet system.

Why Choose This Card? At $300–$350, it is one of the best cards in its class, combining modern technology and mobility. However, for professional work or gaming at 1440p, it’s advisable to consider more powerful models.

Basic

Label Name

AMD

Platform

Mobile

Launch Date

May 2019

Model Name

Radeon RX 640 Mobile

Generation

Mobility Radeon

Base Clock

1082MHz

Boost Clock

1218MHz

Bus Interface

PCIe 3.0 x8

Transistors

2,200 million

Compute Units

TMUs

Texture Mapping Units (TMUs) serve as components of the GPU, which are capable of rotating, scaling, and distorting binary images, and then placing them as textures onto any plane of a given 3D model. This process is called texture mapping.

Foundry

GlobalFoundries

Process Size

14 nm

Architecture

GCN 4.0

Memory Specifications

Memory Size

2GB

Memory Type

GDDR5

Memory Bus

The memory bus width refers to the number of bits of data that the video memory can transfer within a single clock cycle. The larger the bus width, the greater the amount of data that can be transmitted instantaneously, making it one of the crucial parameters of video memory. The memory bandwidth is calculated as: Memory Bandwidth = Memory Frequency x Memory Bus Width / 8. Therefore, when the memory frequencies are similar, the memory bus width will determine the size of the memory bandwidth.

64bit

Memory Clock

1500MHz

Bandwidth

Memory bandwidth refers to the data transfer rate between the graphics chip and the video memory. It is measured in bytes per second, and the formula to calculate it is: memory bandwidth = working frequency × memory bus width / 8 bits.

48.00 GB/s

Theoretical Performance

Pixel Rate

Pixel fill rate refers to the number of pixels a graphics processing unit (GPU) can render per second, measured in MPixels/s (million pixels per second) or GPixels/s (billion pixels per second). It is the most commonly used metric to evaluate the pixel processing performance of a graphics card.

19.49 GPixel/s

Texture Rate

Texture fill rate refers to the number of texture map elements (texels) that a GPU can map to pixels in a single second.

48.72 GTexel/s

FP16 (half)

An important metric for measuring GPU performance is floating-point computing capability. Half-precision floating-point numbers (16-bit) are used for applications like machine learning, where lower precision is acceptable. Single-precision floating-point numbers (32-bit) are used for common multimedia and graphics processing tasks, while double-precision floating-point numbers (64-bit) are required for scientific computing that demands a wide numeric range and high accuracy.

1.559 TFLOPS

FP64 (double)

An important metric for measuring GPU performance is floating-point computing capability. Double-precision floating-point numbers (64-bit) are required for scientific computing that demands a wide numeric range and high accuracy, while single-precision floating-point numbers (32-bit) are used for common multimedia and graphics processing tasks. Half-precision floating-point numbers (16-bit) are used for applications like machine learning, where lower precision is acceptable.

97.44 GFLOPS

FP32 (float)

An important metric for measuring GPU performance is floating-point computing capability. Single-precision floating-point numbers (32-bit) are used for common multimedia and graphics processing tasks, while double-precision floating-point numbers (64-bit) are required for scientific computing that demands a wide numeric range and high accuracy. Half-precision floating-point numbers (16-bit) are used for applications like machine learning, where lower precision is acceptable.

1.528 TFLOPS

Miscellaneous

Shading Units

The most fundamental processing unit is the Streaming Processor (SP), where specific instructions and tasks are executed. GPUs perform parallel computing, which means multiple SPs work simultaneously to process tasks.

640

L1 Cache

16 KB (per CU)

L2 Cache

512KB

TDP

50W

Vulkan Version

Vulkan is a cross-platform graphics and compute API by Khronos Group, offering high performance and low CPU overhead. It lets developers control the GPU directly, reduces rendering overhead, and supports multi-threading and multi-core processors.

1.2

OpenCL Version

2.1

OpenGL

4.6

DirectX

12 (12_0)

Power Connectors

None

Shader Model

6.4

ROPs

The Raster Operations Pipeline (ROPs) is primarily responsible for handling lighting and reflection calculations in games, as well as managing effects like anti-aliasing (AA), high resolution, smoke, and fire. The more demanding the anti-aliasing and lighting effects in a game, the higher the performance requirements for the ROPs; otherwise, it may result in a sharp drop in frame rate.

Benchmarks

FP32 (float)

Score

1.528 TFLOPS

Compared to Other GPU

FP32 (float) / TFLOPS

GRID M10 8Q

1.639 +7.3%

Quadro K4100M

1.594 +4.3%

Radeon RX 640 Mobile

1.528

Radeon Vega 9 Mobile

1.468 -3.9%

GeForce GTX 950M

1.41 -7.7%