AMD Instinct MI455X vs AMD Radeon RX 6550S Comparison

Where Each One Wins

The recorded data shows two AMD accelerators with entirely different design targets, and no direct head-to-head benchmark wins are recorded for either part. The AMD Instinct MI455X is positioned as a data center compute accelerator, while the AMD Radeon RX 6550S is a mobile integrated graphics solution. The benchmark database shows zero wins for each in direct comparison, which reflects their disparate roles rather than any performance equivalence.

For compute throughput, the Instinct MI455X dominates. Its FP32 rating of 157.3 TFLOPS versus 4.915 TFLOPS for the RX 6550S indicates a 32-fold advantage in raw single-precision compute. The FP16 figures tell a similar story: the MI455X delivers 157.3 TFLOPS with a 1:1 ratio, while the RX 6550S provides 9.830 TFLOPS with a 2:1 ratio. Any workload that stresses floating-point math, such as AI training or scientific simulation, belongs firmly to the Instinct side.

For graphics and display-oriented tasks, the RX 6550S holds every advantage that matters. It features 32 ROPs with a pixel rate of 76.80 GPixel/s, while the MI455X has zero ROPs and a pixel rate of 0 MPixel/s. The RX 6550S also includes 16 ray tracing cores, a feature entirely absent from the MI455X. The Instinct part has no display outputs whatsoever, while the RX 6550S uses Portable Device Dependent outputs. Any workload requiring rasterization, ray tracing, or visual output cannot use the MI455X at all.

The memory architecture reinforces this split. The MI455X carries 432 GB of HBM4 on a 24576-bit bus with 23.3 TB/s bandwidth. The RX 6550S has 4 GB of GDDR6 on a 64-bit bus with 128.0 GB/s. For large model inference or massive data sets, the MI455X provides over 180 times the memory capacity and over 180 times the bandwidth. The RX 6550S suits small, latency-sensitive graphics workloads in portable devices.

Architecture Differences

The MI455X uses the MI450 256CU chip built on CDNA 5.0 architecture, fabricated on a 2 nm process at TSMC. The RX 6550S uses the Navi 24 chip built on RDNA 2.0 architecture, fabricated on a 6 nm process, also at TSMC. These are entirely different compute architectures: CDNA 5.0 targets compute density, while RDNA 2.0 targets graphics efficiency.

Transistor counts differ by a factor of roughly 59. The MI455X integrates 320,000 million transistors on a 2990 mm² die, yielding a density of 107.0M transistors per mm². The RX 6550S integrates 5,400 million transistors on a 107 mm² die, yielding 50.5M per mm². The MI455X uses a far larger die with more than double the transistor density.

The MI455X has 32768 shading units and 1024 texture mapping units, with zero ROPs. The RX 6550S has 1024 shading units, 64 TMUs, and 32 ROPs. The MI455X's texture rate reaches 2,457.6 GTexel/s versus 153.6 GTexel/s for the RX 6550S. The MI455X has no ray tracing cores; the RX 6550S has 16.

Both parts run at a 2400 MHz boost clock. The base clocks differ: 1000 MHz for the MI455X, 2000 MHz for the RX 6550S. The RX 6550S also lists a game clock of 2170 MHz, which the MI455X does not have. Memory clocks differ substantially: the MI455X runs HBM4 at 1900 MHz (7.6 Gbps effective), while the RX 6550S runs GDDR6 at 2000 MHz (16 Gbps effective). The MI455X's memory bus width of 24576 bit dwarfs the RX 6550S's 64-bit bus, leading to the massive bandwidth gap.

The MI455X uses an EAM Module slot width with no power connectors and no display outputs. The RX 6550S is an IGP with no power connectors and Portable Device Dependent outputs. The MI455X requires a suggested PSU of 2700 W, while the RX 6550S lists no suggested PSU. The MI455X uses PCIe 6.0 x16; the RX 6550S uses PCIe 4.0 x4.

API support differs completely. The MI455X lists DirectX, OpenGL, and Vulkan as N/A. The RX 6550S supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. The RX 6550S is marked Active in production status, while the MI455X has no production status recorded.

The Verdict

The data indicates two products for separate markets with no direct competition. The AMD Instinct MI455X is a compute accelerator for data center workloads. Its 157.3 TFLOPS FP32, 432 GB HBM4 memory, 23.3 TB/s bandwidth, and 2300 W TDP define it as a high-throughput device for large-scale computation. Its zero ROPs, zero display outputs, and N/A graphics APIs confirm it cannot perform traditional graphics tasks.

The AMD Radeon RX 6550S is a mobile graphics processor for portable devices. Its 50 W TDP, 4 GB GDDR6, 76.80 GPixel/s pixel rate, 16 ray tracing cores, and full DirectX 12 Ultimate support define it as a graphics solution. Its 4.915 TFLOPS FP32 and 128.0 GB/s bandwidth are modest by data center standards but appropriate for its IGP form factor.

Selection depends entirely on workload type. For compute-heavy tasks such as AI training, scientific computing, or data processing, the MI455X is the only viable option from these two. For graphics rendering, gaming, or display output in a portable system, the RX 6550S is the only option that supports these functions at all. Neither part can substitute for the other.

FAQ

Q: Which GPU has higher FP32 compute performance?

A: The AMD Instinct MI455X delivers 157.3 TFLOPS FP32, compared to 4.915 TFLOPS for the AMD Radeon RX 6550S, a 32-fold advantage for the Instinct part.

Q: Does the AMD Instinct MI455X support ray tracing?

A: No. The MI455X has no ray tracing cores listed. The AMD Radeon RX 6550S includes 16 ray tracing cores.

Q: What memory types do these two GPUs use?

A: The AMD Instinct MI455X uses 432 GB of HBM4 with a 24576-bit bus and 23.3 TB/s bandwidth. The AMD Radeon RX 6550S uses 4 GB of GDDR6 with a 64-bit bus and 128.0 GB/s bandwidth.

Q: Can the AMD Instinct MI455X output to a display?

A: No. The MI455X lists "No outputs" for display outputs. The AMD Radeon RX 6550S lists Portable Device Dependent outputs.

Q: Which GPU has a higher pixel rate?

A: The AMD Radeon RX 6550S has a pixel rate of 76.80 GPixel/s. The AMD Instinct MI455X has a pixel rate of 0 MPixel/s, as it has zero ROPs.

Q: What are the TDP differences between these parts?

A: The AMD Instinct MI455X has a TDP of 2300 W with a suggested PSU of 2700 W. The AMD Radeon RX 6550S has a TDP of 50 W and no suggested PSU listed.

Head-to-Head Benchmarks

The benchmark database records no head-to-head benchmark results between these two GPUs. The winsA and winsB fields are both zero. This absence of direct comparison data reflects the fundamental incompatibility of their use cases: one is a compute accelerator with no graphics output, the other is a mobile graphics processor with no compute-oriented design.

Despite the lack of direct benchmarks, the specification data allows for meaningful comparisons. In FP32 compute, the MI455X's 157.3 TFLOPS versus the RX 6550S's 4.915 TFLOPS represents a 32x gap. In FP16, the MI455X's 157.3 TFLOPS (1:1) versus the RX 6550S's 9.830 TFLOPS (2:1) shows a 16x gap. The MI455X's texture rate of 2,457.6 GTexel/s versus 153.6 GTexel/s for the RX 6550S is a 16x difference.

Memory bandwidth presents the largest relative gap. The MI455X's 23.3 TB/s versus the RX 6550S's 128.0 GB/s is a difference of over 180 times. Memory capacity follows a similar pattern: 432 GB versus 4 GB, again over 100 times more on the Instinct side.

The RX 6550S wins in graphics-specific metrics. Its pixel rate of 76.80 GPixel/s compares to 0 MPixel/s for the MI455X. The RX 6550S has 32 ROPs versus zero. The RX 6550S supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, while the MI455X lists N/A for all three APIs.

Clock speeds show a mixed picture. Both parts boost to 2400 MHz. The RX 6550S has a higher base clock at 2000 MHz versus 1000 MHz for the MI455X. The RX 6550S also lists a game clock of 2170 MHz, which the MI455X does not have. The RX 6550S runs its memory at 2000 MHz (16 Gbps effective), while the MI455X runs at 1900 MHz (7.6 Gbps effective), though the MI455X's much wider bus compensates dramatically.

Specification Differences

The two GPUs differ across nearly every recorded specification. The MI455X uses the MI450 256CU chip on CDNA 5.0 architecture, fabricated on a 2 nm process. The RX 6550S uses the Navi 24 chip on RDNA 2.0 architecture, fabricated on a 6 nm process. Both use TSMC as foundry.

Transistor count: the MI455X has 320,000 million transistors on a 2990 mm² die. The RX 6550S has 5,400 million transistors on a 107 mm² die. Transistor density: 107.0M per mm² for the MI455X, 50.5M per mm² for the RX 6550S.

Shading units: 32768 for the MI455X, 1024 for the RX 6550S. TMUs: 1024 for the MI455X, 64 for the RX 6550S. ROPs: 0 for the MI455X, 32 for the RX 6550S. Ray tracing cores: none for the MI455X, 16 for the RX 6550S.

Pixel rate: 0 MPixel/s for the MI455X, 76.80 GPixel/s for the RX 6550S. Texture rate: 2,457.6 GTexel/s for the MI455X, 153.6 GTexel/s for the RX 6550S. FP32: 157.3 TFLOPS for the MI455X, 4.915 TFLOPS for the RX 6550S. FP16: 157.3 TFLOPS (1:1) for the MI455X, 9.830 TFLOPS (2:1) for the RX 6550S.

Base clock: 1000 MHz for the MI455X, 2000 MHz for the RX 6550S. Boost clock: 2400 MHz for both. Game clock: none for the MI455X, 2170 MHz for the RX 6550S. Memory clock: 1900 MHz (7.6 Gbps effective) for the MI455X, 2000 MHz (16 Gbps effective) for the RX 6550S.

Memory size: 432 GB for the MI455X, 4 GB for the RX 6550S. Memory type: HBM4 for the MI455X, GDDR6 for the RX 6550S. Bus width: 24576 bit for the MI455X, 64 bit for the RX 6550S. Bandwidth: 23.3 TB/s for the MI455X, 128.0 GB/s for the RX 6550S.

TDP: 2300 W for the MI455X, 50 W for the RX 6550S. Slot width: EAM Module for the MI455X, IGP for the RX 6550S. Power connectors: None for both. Suggested PSU: 2700 W for the MI455X, none for the RX 6550S. Bus interface: PCIe 6.0 x16 for the MI455X, PCIe 4.0 x4 for the RX 6550S.

Display outputs: No outputs for the MI455X, Portable Device Dependent for the RX 6550S. DirectX: N/A for the MI455X, 12 Ultimate (12_2) for the RX 6550S. OpenGL: N/A for the MI455X, 4.6 for the RX 6550S. Vulkan: N/A for the MI455X, 1.4 for the RX 6550S. Production status: none for the MI455X, Active for the RX 6550S. Release date: 2026-07-22 for the MI455X, 2023-01-03 for the RX 6550S.