AMD Instinct MI455X vs AMD Radeon RX 7400 Comparison

Head-to-Head Benchmarks

The recorded data shows a decisive performance gap between the AMD Instinct MI455X and the AMD Radeon RX 7400, though direct head-to-head benchmark comparisons are not available in the database. The Instinct MI455X carries no individual benchmark scores, while the Radeon RX 7400 has eight recorded results spanning 3DMark and PassMark suites. The absence of overlapping test data means the comparison relies on the architectural specifications and the RX 7400's distinct benchmark profile.

The Radeon RX 7400 delivers its strongest result in PassMark G3D with a score of 11,897, which represents its primary graphics performance marker. Its compute-oriented PassMark GPU Compute score sits at 5,152, roughly 43% of the G3D figure, indicating a card more optimized for rasterization than general-purpose compute. The DirectX 9 score of 176 far exceeds the DirectX 10 score of 59, the DirectX 11 score of 97, and the DirectX 12 score of 44, suggesting legacy API workloads run relatively stronger on this architecture. The 3DMark Steel Nomad DX12 result of 1,103 provides a modern gaming workload data point, while the PassMark G2D score of 1,209 reflects 2D desktop acceleration capability.

The Instinct MI455X, by contrast, posts an average benchmark score of zero and occupies the 50th percentile among all GPUs, precisely the median position. The RX 7400 sits at the 17th percentile, meaning it ranks below the majority of recorded graphics processors. The MI455X's theoretical compute throughput dwarfs the RX 7400's measured results: 157.3 TFLOPS FP32 versus 16.49 TFLOPS FP32, a ratio of roughly 9.5 to 1. Texture rate follows a similar pattern, with the MI455X delivering 2,457.6 GTexel/s against the RX 7400's 257.6 GTexel/s. Pixel rate inverts the trend, as the MI455X records 0 MPixel/s while the RX 7400 achieves 147.2 GPixel/s, a structural difference rooted in their respective render pipelines.

Architecture Differences

The two AMD parts diverge at nearly every architectural layer. The Instinct MI455X uses the MI450 256CU chip built on CDNA 5.0 architecture, while the RX 7400 uses the Navi 33 chip with RDNA 3.0 architecture. These represent fundamentally different design philosophies: CDNA 5.0 targets accelerated compute and data-center workloads, while RDNA 3.0 targets graphics rendering and consumer gaming.

Manufacturing processes separate them sharply. The MI455X uses a 2 nm process at TSMC, while the RX 7400 uses a 6 nm process, also at TSMC. Transistor counts differ by an order of magnitude: the MI455X packs 320,000 million transistors across a 2,990 mm² die, producing a density of 107.0M transistors per mm². The RX 7400 contains 13,300 million transistors on a 204 mm² die, yielding 65.2M transistors per mm². The MI455X's die is nearly fifteen times larger in physical area and carries over twenty-four times the transistor count.

Memory subsystems could hardly be more different. The MI455X features 432 GB of HBM4 memory on a 24,576-bit bus, delivering 23.3 TB/s of bandwidth. The RX 7400 uses 8 GB of GDDR6 on a 128-bit bus, with 288.0 GB/s of bandwidth. The MI455X's memory bandwidth exceeds the RX 7400's by a factor of approximately 81. The MI455X runs memory at 1900 MHz with 7.6 Gbps effective speed, while the RX 7400's memory operates at 2250 MHz with 18 Gbps effective speed, illustrating how bus width rather than clock speed determines overall bandwidth.

Shader resources follow the same trajectory. The MI455X contains 32,768 shading units and 1,024 texture mapping units, with no ROPs recorded. The RX 7400 has 1,792 shading units, 112 TMUs, and 64 ROPs. The MI455X also omits dedicated ray tracing cores, while the RX 7400 includes 28 RT cores. FP16 throughput on the MI455X matches its FP32 at 157.3 TFLOPS in a 1:1 ratio, whereas the RX 7400 doubles its FP16 to 32.97 TFLOPS via a 2:1 ratio, a consumer-oriented configuration for mixed-precision workloads.

Clock speeds show a narrower gap. The MI455X bases at 1000 MHz and boosts to 2400 MHz, while the RX 7400 bases at 1452 MHz, boosts to 2300 MHz, and carries a 2200 MHz game clock. Power and physical requirements diverge completely: the MI455X draws 2300 W TDP with a 2700 W suggested PSU, while the RX 7400 sips 43 W TDP with a 200 W suggested PSU. The MI455X uses an EAM module slot width with no power connectors and no display outputs, while the RX 7400 is dual-slot, uses one 6-pin connector, and outputs via 1x HDMI 2.1a and 3x DisplayPort 2.1. The MI455X interfaces over PCIe 6.0 x16, while the RX 7400 uses PCIe 4.0 x8.

Where Each One Wins

The MI455X wins decisively in compute density, memory capacity, and bandwidth. Any workload that scales with raw FP32 throughput, massive memory pools, or extreme memory bandwidth favors the MI455X. Its 157.3 TFLOPS FP32, 432 GB HBM4, and 23.3 TB/s bandwidth target large-scale AI training, scientific simulation, and data-center inference. The architecture's CDNA 5.0 lineage and 2 nm process node suggest optimized energy-per-compute for sustained server workloads, though the 2300 W TDP requires industrial power delivery. The MI455X's 50th percentile ranking with no recorded benchmark scores indicates the database lacks gaming or consumer workload measurements for this part, reinforcing its specialized positioning.

The RX 7400 wins in every scenario involving rasterized graphics output. Its 64 ROPs and 147.2 GPixel/s pixel rate enable actual display rendering, which the MI455X cannot perform at all given its lack of display outputs and zero pixel rate. The RX 7400's 28 RT cores provide hardware ray tracing support, absent from the MI455X. The RX 7400 also supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, while the MI455X lists no API support across any of those interfaces. For gaming, desktop use, or any workload requiring a video output, the RX 7400 is the only functional choice between these two parts.

The RX 7400's nearest rivals in the database reinforce its performance tier. The AMD Radeon 8040S averages 2,440, just 1.1% above the RX 7400's average of 2,467. The NVIDIA GeForce 710M scores 2,433, a 1.4% delta; the Intel HD Graphics 610 scores 2,425, a 1.8% delta; and the NVIDIA GeForce GT 710M scores 2,422, a 1.9% delta. These margins indicate the RX 7400 clusters with low-end integrated and entry-level discrete GPUs from prior generations. The MI455X, with no rivals listed, occupies an entirely separate performance space.

FAQ

Q: How much faster is the Instinct MI455X than the Radeon RX 7400 in FP32 compute?

A: The MI455X delivers 157.3 TFLOPS FP32, while the RX 7400 delivers 16.49 TFLOPS FP32, making the MI455X approximately 9.5 times faster in raw single-precision floating-point throughput.

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

A: No. The MI455X has no display outputs and a pixel rate of 0 MPixel/s, meaning it cannot render frames for display. The RX 7400 provides 1x HDMI 2.1a and 3x DisplayPort 2.1 outputs with a 147.2 GPixel/s pixel rate.

Q: What memory configurations do these two GPUs use?

A: The MI455X uses 432 GB of HBM4 memory on a 24,576-bit bus with 23.3 TB/s bandwidth. The RX 7400 uses 8 GB of GDDR6 memory on a 128-bit bus with 288.0 GB/s bandwidth.

Q: How do the power requirements compare?

A: The MI455X has a 2300 W TDP and requires a 2700 W suggested PSU, while the RX 7400 has a 43 W TDP and a 200 W suggested PSU. The MI455X uses no power connectors due to its EAM module design, while the RX 7400 uses one 6-pin connector.

Q: Which GPU supports hardware ray tracing?

A: Only the RX 7400, which includes 28 RT cores. The MI455X has no ray tracing cores listed in its specifications.

Q: Where does the RX 7400 rank compared to its nearest competitors?

A: The RX 7400 averages 2,467 in benchmark scores, placing it 1.1% above the AMD Radeon 8040S, 1.4% above the NVIDIA GeForce 710M, 1.8% above the Intel HD Graphics 610, and 1.9% above the NVIDIA GeForce GT 710M.

The Verdict

The data presents a clear bifurcation with no meaningful overlap. The Instinct MI455X is a compute accelerator with extreme specifications: 2 nm process, 320,000 million transistors, 432 GB HBM4, 157.3 TFLOPS FP32, and 23.3 TB/s memory bandwidth. It cannot output video, supports no consumer graphics APIs, and consumes 2300 W. It sits at the 50th percentile in the database, which appears to reflect its position as a median performer across all recorded GPUs, though no individual benchmarks exist for it.

The Radeon RX 7400 is a low-power graphics card with a 43 W TDP, 8 GB GDDR6, 28 RT cores, and full display output support. Its benchmark results place it at the 17th percentile, and its nearest rivals are all entry-level or integrated graphics solutions. Its best score, 11,897 in PassMark G3D, demonstrates functional rasterization capability, while its 1,103 in 3DMark Steel Nomad reflects modest modern gaming performance.

The choice between these two reduces to workload type. The MI455X suits compute environments requiring massive memory bandwidth and FP32 throughput, accepting the absence of display output and consumer API support. The RX 7400 suits conventional graphics tasks, gaming, and desktop use, accepting far lower compute throughput and memory capacity. The database records no benchmark where both parts compete, and the architectural chasm between 2 nm CDNA 5.0 and 6 nm RDNA 3.0 confirms they target disjoint market segments. The MI455X's 2,457.6 GTexel/s texture rate versus the RX 7400's 257.6 GTexel/s, combined with the MI455X's zero pixel rate versus the RX 7400's 147.2 GPixel/s, captures the essential trade-off: compute throughput without graphics output, or graphics output without extreme compute.