ATI Radeon HD 4855
AMD graphics card specifications and benchmark scores
At a Glance
AMDATI Radeon HD 4855 Specifications
ATI Radeon HD 4855 GPU Core
Shader units and compute resources
The ATI Radeon HD 4855 GPU core specifications define its raw processing power for graphics and compute workloads. Shading units (also called CUDA cores, stream processors, or execution units depending on manufacturer) handle the parallel calculations required for rendering. TMUs (Texture Mapping Units) process texture data, while ROPs (Render Output Units) handle final pixel output. Higher shader counts generally translate to better GPU benchmark performance, especially in demanding games and 3D applications.
ATI Radeon HD 4855 Clock Speeds
GPU and memory frequencies
Clock speeds directly impact the ATI Radeon HD 4855's performance in GPU benchmarks and real-world gaming. The base clock represents the minimum guaranteed frequency, while the boost clock indicates peak performance under optimal thermal conditions. Memory clock speed affects texture loading and frame buffer operations. The ATI Radeon HD 4855 by AMD dynamically adjusts frequencies based on workload, temperature, and power limits to maximize performance while maintaining stability.
AMD's ATI Radeon HD 4855 Memory
VRAM capacity and bandwidth
VRAM (Video RAM) is dedicated memory for storing textures, frame buffers, and shader data. The ATI Radeon HD 4855's memory capacity determines how well it handles high-resolution textures and multiple displays. Memory bandwidth, measured in GB/s, affects how quickly data moves between the GPU and VRAM. Higher bandwidth improves performance in memory-intensive scenarios like 4K gaming. The memory bus width and type (GDDR6, GDDR6X, HBM) significantly influence overall GPU benchmark scores.
ATI Radeon HD 4855 by AMD Cache
On-chip cache hierarchy
On-chip cache provides ultra-fast data access for the ATI Radeon HD 4855, reducing the need to fetch data from slower VRAM. L1 and L2 caches store frequently accessed data close to the compute units. AMD's Infinity Cache (L3) dramatically increases effective bandwidth, improving GPU benchmark performance without requiring wider memory buses. Larger cache sizes help maintain high frame rates in memory-bound scenarios and reduce power consumption by minimizing VRAM accesses.
ATI Radeon HD 4855 Theoretical Performance
Compute and fill rates
Theoretical performance metrics provide a baseline for comparing the ATI Radeon HD 4855 against other graphics cards. FP32 (single-precision) performance, measured in TFLOPS, indicates compute capability for gaming and general GPU workloads. FP64 (double-precision) matters for scientific computing. Pixel and texture fill rates determine how quickly the GPU can render complex scenes. While real-world GPU benchmark results depend on many factors, these specifications help predict relative performance levels.
TeraScale Architecture & Process
Manufacturing and design details
The ATI Radeon HD 4855 is built on AMD's TeraScale architecture, which defines how the GPU processes graphics and compute workloads. The manufacturing process node affects power efficiency, thermal characteristics, and maximum clock speeds. Smaller process nodes pack more transistors into the same die area, enabling higher performance per watt. Understanding the architecture helps predict how the ATI Radeon HD 4855 will perform in GPU benchmarks compared to previous generations.
AMD's ATI Radeon HD 4855 Power & Thermal
TDP and power requirements
Power specifications for the ATI Radeon HD 4855 determine PSU requirements and thermal management needs. TDP (Thermal Design Power) indicates the heat output under typical loads, guiding cooler selection. Power connector requirements ensure adequate power delivery for stable operation during demanding GPU benchmarks. The suggested PSU wattage accounts for the entire system, not just the graphics card. Efficient power delivery enables the ATI Radeon HD 4855 to maintain boost clocks without throttling.
ATI Radeon HD 4855 by AMD Physical & Connectivity
Dimensions and outputs
Physical dimensions of the ATI Radeon HD 4855 are critical for case compatibility. Card length, height, and slot width determine whether it fits in your chassis. The PCIe interface version affects bandwidth for communication with the CPU. Display outputs define monitor connectivity options, with modern cards supporting multiple high-resolution displays simultaneously. Verify these specifications against your case and motherboard before purchasing to ensure a proper fit.
AMD API Support
Graphics and compute APIs
API support determines which games and applications can fully utilize the ATI Radeon HD 4855. DirectX 12 Ultimate enables advanced features like ray tracing and variable rate shading. Vulkan provides cross-platform graphics capabilities with low-level hardware access. OpenGL remains important for professional applications and older games. CUDA (NVIDIA) and OpenCL enable GPU compute for video editing, 3D rendering, and scientific applications. Higher API versions unlock newer graphical features in GPU benchmarks and games.
ATI Radeon HD 4855 Product Information
Release and pricing details
The ATI Radeon HD 4855 is manufactured by AMD as part of their graphics card lineup. Release date and launch pricing provide context for comparing GPU benchmark results with competing products from the same era. Understanding the product lifecycle helps evaluate whether the ATI Radeon HD 4855 by AMD represents good value at current market prices. Predecessor and successor information aids in tracking generational improvements and planning future upgrades.
ATI Radeon HD 4855 Benchmark Scores
No benchmark data available for this GPU.
About ATI Radeon HD 4855
The ATI Radeon HD 4855 is a legacy, end-of-life graphics card built on AMD's TeraScale architecture, utilizing the RV770 chip fabricated on a 55 nm process at TSMC. With a die size of 256 mm² containing 956 million transistors, it achieves a transistor density of 3.7 million per mm². The card is positioned at the 50th percentile in the benchmark database, indicating it sits squarely in the mid-range of all tracked GPUs, though its average benchmark score is recorded as zero, meaning performance data is derived from its architectural characteristics rather than direct measurements.
Benchmark Performance
The HD 4855 delivers a FP32 performance of 736.0 GFLOPS, a figure that defines its compute ceiling for shader operations. This is supported by 640 shading units, 32 texture mapping units (TMUs), and 16 raster output units (ROPs). The card's pixel fill rate is 9.200 GPixel/s, while its texture fill rate reaches 18.40 GTexel/s. These numbers indicate a card designed for 1080p gaming in its era, with the pixel rate suggesting it could handle moderate resolutions without bottlenecking on rasterization.
The benchmark database places this card at the 50th percentile among all GPUs, which is a median position. Because the nearestRivals array is empty, direct percentage deltas against specific competitors cannot be provided. However, the architectural data allows for interpretation: the 736.0 GFLOPS FP32 throughput is roughly half of what high-end cards of the same generation achieved, positioning it as a mainstream performer. The 18.40 GTexel/s texture rate suggests that texture-heavy workloads would be adequately served at lower resolutions, but the 16 ROPs could become a limiting factor for high-resolution anti-aliasing.
The card's average benchmark score of zero is notable; this does not imply no performance, but rather that no synthetic benchmark runs have been recorded in the database. Consequently, all performance analysis must rely on the fill rates, compute throughput, and memory bandwidth. The 50th percentile ranking, however, provides a global context: half of all GPUs in the database are faster, and half are slower, making this a true mid-pack option for legacy applications.
Ray Tracing and Feature Set
The HD 4855 does not include dedicated ray tracing cores or tensor cores, as these are modern additions absent from the TeraScale architecture. The card's API support reflects its 2010 release: it supports DirectX 10.1 with a shader model of 10_1, and OpenGL 3.3. There is no Vulkan support, which limits its compatibility with modern titles that rely on this low-overhead API. The absence of hardware ray tracing means any ray-traced effects would have to be computed via shader-based methods on the 640 shading units, which would be prohibitively slow given the 736.0 GFLOPS FP32 ceiling.
The DirectX 10.1 support is a critical limitation. Games requiring DirectX 11 or 12 features, such as tessellation or compute shaders, will not run. The OpenGL 3.3 support is similarly dated, restricting compatibility with newer OpenGL-based applications. The card's display outputs include 1x DVI, 1x HDMI 1.3a, and 1x VGA, which covers legacy monitors but lacks DisplayPort connectivity. The HDMI 1.3a standard supports 1080p output but cannot handle 4K resolutions at higher refresh rates.
Memory Subsystem
The HD 4855 is equipped with 512 MB of GDDR5 memory on a 256-bit bus, yielding a memory bandwidth of 115.2 GB/s. The memory clock runs at 900 MHz, translating to 3.6 Gbps effective data rate. This configuration was competitive for its time, but the 512 MB capacity is the primary bottleneck for modern workloads. At high resolutions, the limited frame buffer will cause texture thrashing and stuttering, as the card cannot hold large texture sets or high-resolution buffers.
The 256-bit bus width is a strong point, providing a balanced memory interface that maximizes the GDDR5 bandwidth. The 115.2 GB/s bandwidth is sufficient for the card's 736.0 GFLOPS compute throughput, meaning the memory subsystem is not starving the shaders in most scenarios. However, for 1440p or 4K gaming, the bandwidth and capacity will both prove inadequate. The 900 MHz memory clock is modest, but the GDDR5 type ensures it outperforms the GDDR3 memory found in older cards with similar bus widths.
For high-resolution workloads, the 512 MB VRAM is the defining weakness. Even at 1080p, modern games with high-resolution textures will exceed this capacity, forcing the card to fall back to system memory via the PCIe 2.0 x16 interface, which has significantly lower bandwidth. The card's 115.2 GB/s bandwidth is only useful if the data fits within the 512 MB frame buffer; once exceeded, performance collapses.
Power and Cooling
The HD 4855 has a thermal design power (TDP) of 110 W, which is modest by modern standards. The card requires a single 6-pin power connector and recommends a 300 W power supply unit. These figures indicate a card that is relatively power-efficient for its era, drawing less than half of what flagship cards of the same generation consumed. The dual-slot cooling solution is adequate for the 110 W TDP, and the card's physical dimensions are 220 mm in length, equivalent to 8.7 inches, making it compatible with most mid-tower cases.
The 55 nm process node is large by today's standards, but the 110 W TDP means thermal management is straightforward. The card does not feature any auxiliary power beyond the single 6-pin connector, so users with older power supplies lacking this connector would need an adapter. The 300 W PSU recommendation is conservative, allowing for a typical system configuration with a mainstream CPU and a few drives. Overclocking headroom is not specified, but the modest TDP suggests some thermal margin exists for enthusiasts, though the 55 nm process limits frequency scaling.
How It Compares
The nearestRivals array is empty in the FACT PACK, so no direct comparisons to specific rival cards can be made. The card's 50th percentile ranking places it in the middle of the database, but without named rivals, the analysis must rely on its own specifications. Compared to its predecessor, the Radeon R600 series, the HD 4855's RV770 chip offers a more efficient architecture with higher transistor density (3.7M / mm²). Its successor, the Evergreen series, would supersede it with newer features, but the HD 4855 remains a capable legacy option.
In the absence of rival data, the card's position can be inferred from its FP32 performance and memory bandwidth. The 736.0 GFLOPS and 115.2 GB/s are balanced figures that suggest it would compete with other mid-range cards of the 2009-2010 era. The lack of DirectX 11 support, however, puts it at a disadvantage against cards that launched later with that API. The 50th percentile ranking confirms it is neither a low-end nor a high-end part, but a solid mainstream choice for its generation.
Who Should Consider It
The HD 4855 is suitable for users running legacy applications, particularly games from the DirectX 10 era or earlier. For 1080p gaming with medium settings in titles that support DirectX 10.1, the card's 736.0 GFLOPS and 115.2 GB/s bandwidth are sufficient. The 9.200 GPixel/s pixel rate ensures that rasterization is not a bottleneck at this resolution. However, for high-resolution gaming beyond 1080p, the 512 MB VRAM will be a severe limitation, causing texture streaming issues and reduced frame rates.
Users with older systems that still rely on PCIe 2.0 x16 slots will find this card compatible, and the 110 W TDP means it can be powered by a 300 W PSU. The card is not suitable for modern gaming, as the DirectX 10.1 API support excludes most current titles. For those seeking a retro build or a basic display adapter for non-gaming tasks, the HD 4855 offers adequate performance. The 50th percentile ranking suggests it is a balanced performer for its time, but modern integrated graphics have surpassed it in both features and efficiency.
FAQ
Q: Does the ATI Radeon HD 4855 support DirectX 11 or 12?
A: No, the card supports DirectX 10.1 with shader model 10_1. It does not support DirectX 11 or 12, limiting its compatibility to older games.
Q: What is the maximum memory bandwidth of the HD 4855?
A: The memory bandwidth is 115.2 GB/s, achieved with 512 MB of GDDR5 memory on a 256-bit bus, running at a 900 MHz memory clock (3.6 Gbps effective).
Q: How much power does the HD 4855 require?
A: The card has a TDP of 110 W, requires a single 6-pin power connector, and recommends a 300 W power supply unit for the system.
Q: Can the HD 4855 handle 4K resolution gaming?
A: No, the 512 MB VRAM and 115.2 GB/s bandwidth are insufficient for 4K gaming. The card also has a pixel rate of 9.200 GPixel/s, which would bottleneck at such high resolutions.
Q: Does the HD 4855 support Vulkan or ray tracing?
A: No, the card has no Vulkan support and no dedicated ray tracing cores. It only supports OpenGL 3.3 and DirectX 10.1.
Q: What is the physical size of the HD 4855?
A: The card is 220 mm (8.7 inches) in length and occupies a dual-slot width in the case. It has a 55 nm process node and a die size of 256 mm².
The NVIDIA Equivalent of ATI Radeon HD 4855
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