AMD Instinct MI355X vs AMD Radeon RX 7800 XT Comparison

Head-to-Head Benchmarks

The data shows no direct head-to-head benchmark results between the AMD Instinct MI355X and the AMD Radeon RX 7800 XT. The Instinct MI355X has no recorded benchmark scores in the database, with an average benchmark score of zero and a percentile ranking of 50 among all GPUs. The Radeon RX 7800 XT, by contrast, has ten recorded benchmark entries across multiple test suites, delivering an average benchmark score of 11627 and a percentile ranking of 51.

The Radeon RX 7800 XT demonstrates its strongest results in specific test categories. In PassMark G3D, it scores 24176, which represents the highest single test result among its recorded benchmarks. The Geekbench Vulkan test produces a score of 54228, indicating strong graphics API performance. The Geekbench OpenCL score reaches 18290, while PassMark GPU Compute records 13473. DirectX-specific results show 121 for DirectX 10, 249 for DirectX 11, 93 for DirectX 12, and 304 for DirectX 9. The PassMark G2D test yields 1177.

The Instinct MI355X has no comparable benchmark data, so relative performance between the two cannot be established through direct measurement. The nearest rivals for the Radeon RX 7800 XT provide context for its standing: the NVIDIA GeForce GTX 1660 scores 11680, which is 0.5 percent ahead of the RX 7800 XT. The AMD Radeon Pro 5500M scores 11528, putting it 0.9 percent behind. The NVIDIA Tesla K20c scores 11479, which is 1.3 percent behind. The AMD Radeon RX 6500 XT scores 11842, placing it 1.8 percent ahead.

The benchmark data indicates the Radeon RX 7800 XT sits in a narrow competitive band, with all four nearest rivals within 1.8 percent of its average score. The absence of benchmark records for the Instinct MI355X means the database contains no measured basis for comparing their computational output.

Where Each One Wins

The Radeon RX 7800 XT wins in every measurable category because it is the only one of the two with recorded benchmark results. Its PassMark DirectX 9 score of 304 exceeds its DirectX 11 score of 249, which in turn exceeds the DirectX 10 score of 121 and the DirectX 12 score of 93. This pattern suggests legacy DirectX workloads perform more strongly than modern DirectX 12 tasks on this hardware.

For compute-oriented tasks, the Geekbench OpenCL score of 18290 and PassMark GPU Compute score of 13473 indicate solid general-purpose throughput. The Geekbench Vulkan score of 54228 shows particularly strong performance in Vulkan-based applications, which is consistent with the card's support for Vulkan 1.4.

The Instinct MI355X has no wins in any benchmark category, as no benchmark scores exist for it in the database. The card's specifications, however, point toward a different performance domain. With 16384 shading units, 1024 texture mapping units, and an FP32 rating of 78.64 TFLOPS, the Instinct MI355X targets compute workloads rather than graphics rendering. Its texture rate of 2457.6 GTexel/s and memory bandwidth of 8.19 TB/s suggest massive data throughput capabilities. The Radeon RX 7800 XT, with 3840 shading units, 240 texture mapping units, and 96 render output units, delivers 37.32 TFLOPS FP32 and a texture rate of 583.2 GTexel/s.

Architecture Differences

The two accelerators belong to different AMD architectures and serve fundamentally different purposes. The Instinct MI355X uses CDNA 4.0 architecture on the MI350 256CU chip, built on a 3 nm process at TSMC. The Radeon RX 7800 XT uses RDNA 3.0 architecture on the Navi 32 chip, built on a 5 nm process, also at TSMC.

Transistor counts differ substantially. The Instinct MI355X packs 185,000 million transistors on a 2380 mm² die, resulting in a transistor density of 77.7 million per square millimeter. The Radeon RX 7800 XT contains 28,100 million transistors on a 346 mm² die, yielding a higher density of 81.2 million per square millimeter despite the larger process node.

Memory configurations could hardly be more different. The Instinct MI355X features 288 GB of HBM3e memory on an 8192-bit bus, delivering 8.19 TB/s of bandwidth. The Radeon RX 7800 XT uses 16 GB of GDDR6 memory on a 256-bit bus, providing 624.1 GB/s of bandwidth. The Instinct MI355X has no render output units and a pixel rate of 0 MPixel/s, confirming its role as a compute accelerator without a graphics output pipeline. The Radeon RX 7800 XT has 96 render output units and a pixel rate of 233.3 GPixel/s, along with 60 ray tracing cores.

Clock behavior differs as well. The Instinct MI355X runs at a 1000 MHz base clock and 2400 MHz boost clock, with memory at 2000 MHz (8 Gbps effective). The Radeon RX 7800 XT runs at 1295 MHz base, 2430 MHz boost, and 2124 MHz game clock, with memory at 2438 MHz (19.5 Gbps effective). The API support reflects their divergent purposes: the Instinct MI355X lists no DirectX, OpenGL, or Vulkan support, while the Radeon RX 7800 XT supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4.

Form factors and power delivery also diverge sharply. The Instinct MI355X is an OAM module measuring 102 mm by 165 mm, with no power connectors and no display outputs. It carries a TDP of 1400 W and requires an 1800 W suggested power supply. The Radeon RX 7800 XT is a dual-slot card measuring 267 mm by 111 mm by 50 mm, uses two 8-pin power connectors, has a 263 W TDP, and recommends a 600 W power supply. The Instinct MI355X uses PCIe 5.0 x16, while the Radeon RX 7800 XT uses PCIe 4.0 x16.

FAQ

Q: Which GPU has a higher FP32 compute rating?

A: The AMD Instinct MI355X delivers 78.64 TFLOPS FP32, more than double the Radeon RX 7800 XT's 37.32 TFLOPS FP32. The Instinct MI355X also matches its FP16 rating at 78.64 TFLOPS (1:1), while the Radeon RX 7800 XT records 37.32 TFLOPS FP16 (1:1).

Q: How do the memory configurations compare?

A: The Instinct MI355X uses 288 GB of HBM3e memory on an 8192-bit bus with 8.19 TB/s bandwidth. The Radeon RX 7800 XT uses 16 GB of GDDR6 memory on a 256-bit bus with 624.1 GB/s bandwidth. The Instinct MI355X has 18 times the memory capacity and over 13 times the bandwidth.

Q: Which card supports graphics APIs?

A: Only the Radeon RX 7800 XT supports graphics APIs, including DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. The Instinct MI355X lists no DirectX, OpenGL, or Vulkan support, reflecting its compute-only design with no display outputs.

Q: What is the Radeon RX 7800 XT's benchmark standing relative to its nearest rivals?

A: The Radeon RX 7800 XT averages 11627 across its benchmark suite. The NVIDIA GeForce GTX 1660 is 0.5 percent ahead with 11680, the AMD Radeon RX 6500 XT is 1.8 percent ahead with 11842, the AMD Radeon Pro 5500M is 0.9 percent behind with 11528, and the NVIDIA Tesla K20c is 1.3 percent behind with 11479.

Q: What are the power requirements for each?

A: The Instinct MI355X has a 1400 W TDP and suggests an 1800 W power supply. The Radeon RX 7800 XT has a 263 W TDP and suggests a 600 W power supply. The Instinct MI355X uses no power connectors as an OAM module, while the Radeon RX 7800 XT uses two 8-pin connectors.

Q: When were these products released?

A: The Instinct MI355X was released on 2025-06-11, while the Radeon RX 7800 XT was released on 2023-09-05. The Radeon RX 7800 XT has an active production status, while the Instinct MI355X has no recorded production status.

The Verdict

The data presents two accelerators with almost no overlap in intended use. The Instinct MI355X is a compute-focused OAM module with no display outputs, no graphics API support, and no recorded benchmarks. Its specifications target massive parallel throughput: 16384 shading units, 288 GB of HBM3e memory, 8.19 TB/s bandwidth, and 78.64 TFLOPS FP32. The 1400 W TDP and 1800 W suggested power supply indicate a datacenter or server deployment context.

The Radeon RX 7800 XT is a conventional graphics card with full display outputs, complete graphics API support, and a 263 W TDP. Its benchmark results place it in a narrow competitive range, with all nearest rivals within 1.8 percent of its average score of 11627. The percentile ranking of 51 confirms it sits slightly above the median of all GPUs in the database.

For users requiring graphics output, gaming, or general desktop workloads, the Radeon RX 7800 XT is the only viable choice between the two, as the Instinct MI355X cannot drive a display or run graphics applications. For users requiring extreme compute throughput, high memory capacity, or very high bandwidth, the Instinct MI355X offers specifications the Radeon RX 7800 XT cannot approach. The Radeon RX 7800 XT has a launch MSRP of 499 USD. The Instinct MI355X has no recorded launch MSRP.

The absence of benchmark data for the Instinct MI355X means the database cannot quantify its real-world performance. The specification gap, however, is substantial enough to indicate that these products serve entirely different markets with no meaningful overlap in use cases.

Specification Differences

The following specifications differ between the two products:

• Architecture: CDNA 4.0 (Instinct MI355X) vs RDNA 3.0 (Radeon RX 7800 XT)
• Process node: 3 nm (Instinct MI355X) vs 5 nm (Radeon RX 7800 XT)
• Transistors: 185,000 million (Instinct MI355X) vs 28,100 million (Radeon RX 7800 XT)
• Die size: 2380 mm² (Instinct MI355X) vs 346 mm² (Radeon RX 7800 XT)
• Base clock: 1000 MHz (Instinct MI355X) vs 1295 MHz (Radeon RX 7800 XT)
• Memory clock: 2000 MHz 8 Gbps effective (Instinct MI355X) vs 2438 MHz 19.5 Gbps effective (Radeon RX 7800 XT)
• Memory size: 288 GB HBM3e (Instinct MI355X) vs 16 GB GDDR6 (Radeon RX 7800 XT)
• Memory bus width: 8192 bit (Instinct MI355X) vs 256 bit (Radeon RX 7800 XT)
• Memory bandwidth: 8.19 TB/s (Instinct MI355X) vs 624.1 GB/s (Radeon RX 7800 XT)
• Shading units: 16384 (Instinct MI355X) vs 3840 (Radeon RX 7800 XT)
• Texture mapping units: 1024 (Instinct MI355X) vs 240 (Radeon RX 7800 XT)
• Render output units: 0 (Instinct MI355X) vs 96 (Radeon RX 7800 XT)
• Pixel rate: 0 MPixel/s (Instinct MI355X) vs 233.3 GPixel/s (Radeon RX 7800 XT)
• Texture rate: 2457.6 GTexel/s (Instinct MI355X) vs 583.2 GTexel/s (Radeon RX 7800 XT)
• FP32 performance: 78.64 TFLOPS (Instinct MI355X) vs 37.32 TFLOPS (Radeon RX 7800 XT)
• TDP: 1400 W (Instinct MI355X) vs 263 W (Radeon RX 7800 XT)
• Slot width: OAM Module (Instinct MI355X) vs Dual-slot (Radeon RX 7800 XT)
• Power connectors: None (Instinct MI355X) vs 2x 8-pin (Radeon RX 7800 XT)
• Suggested PSU: 1800 W (Instinct MI355X) vs 600 W (Radeon RX 7800 XT)
• Bus interface: PCIe 5.0 x16 (Instinct MI355X) vs PCIe 4.0 x16 (Radeon RX 7800 XT)
• Display outputs: No outputs (Instinct MI355X) vs 1x HDMI 2.1a, 3x DisplayPort 2.1 (Radeon RX 7800 XT)
• DirectX support: N/A (Instinct MI355X) vs 12 Ultimate (12_2) (Radeon RX 7800 XT)
• OpenGL support: N/A (Instinct MI355X) vs 4.6 (Radeon RX 7800 XT)
• Vulkan support: N/A (Instinct MI355X) vs 1.4 (Radeon RX 7800 XT)
• Dimensions: 102 mm x 165 mm (Instinct MI355X) vs 267 mm x 111 mm x 50 mm (Radeon RX 7800 XT)
• Release date: 2025-06-11 (Instinct MI355X) vs 2023-09-05 (Radeon RX 7800 XT)