AMD Instinct MI455X vs AMD Radeon RX 7900 GRE Comparison

Head-to-Head Benchmarks

The recorded data for the AMD Instinct MI455X contains no benchmark scores, while the AMD Radeon RX 7900 GRE has a full set of measurements. The MI455X has an average benchmark score of 0 and a percentile rank of 50 among all GPUs, whereas the RX 7900 GRE posts an average score of 32456 and sits at the 77th percentile. This disparity in available data means direct numerical comparisons are limited, but the RX 7900 GRE's performance profile can be examined against its nearest rivals.

The RX 7900 GRE's strongest result is in Passmark's G3D test, where it scores 27089. This places it 0.2% ahead of the AMD FirePro S10000 (average score 32388) and 0.9% ahead of the AMD Radeon Pro 570X (average score 32176). Conversely, it trails the AMD FirePro S9300 X2 by 0.3% (average score 32540) and the AMD Radeon RX 590 GME by 0.4% (average score 32601). These deltas are narrow, indicating the RX 7900 GRE performs in a tight cluster with those cards in aggregate scoring.

In Geekbench OpenCL, the RX 7900 GRE achieves 175758 points, a substantial figure that reflects strong compute throughput. Its Vulkan score of 99850 is notably lower, suggesting API-specific differences in how the architecture handles workloads. Passmark sub-scores break down as follows: DirectX 9 yields 310, DirectX 11 yields 300, DirectX 10 yields 139, and DirectX 12 yields 107. The DirectX 12 result is the weakest of the group, while the older DirectX 9 and 11 paths perform better. The Passmark G2D score is 1180, and the GPU compute score is 15016.

The MI455X, by contrast, has no recorded benchmarks, so its head-to-head wins cannot be quantified. The database shows winsA as 0 and winsB as 0, meaning neither card has a recorded head-to-head benchmark entry. The MI455X's percentile rank of 50, despite an average score of 0, likely reflects its position in the overall distribution based on hardware specifications rather than measured results. For any comparison, the RX 7900 GRE is the only card with empirical data to analyze.

The Verdict

From the data alone, the AMD Radeon RX 7900 GRE is the only option with measurable performance. Its 77th percentile rank and average benchmark score of 32456 indicate solid standing among all GPUs in the database. The MI455X, with an average score of 0 and no benchmark entries, cannot be evaluated on the same terms. Therefore, for any workload where benchmark results matter, the RX 7900 GRE is the clear choice based on recorded measurements.

The MI455X's hardware specifications suggest it is built for a different purpose entirely. It uses 32768 shading units, 1024 texture mapping units, and zero ROPs, with a pixel rate of 0 MPixel/s. These numbers indicate a compute-oriented accelerator with no display output capability, consistent with its "No outputs" display configuration. The RX 7900 GRE, in contrast, has 5120 shading units, 320 TMUs, 160 ROPs, and an 80-core ray tracing array, making it a fully featured graphics card with display outputs including HDMI 2.1a, DisplayPort 2.1, and USB Type-C.

Users seeking a graphics card for rendering, gaming, or general GPU compute should select the RX 7900 GRE, as its benchmark scores and feature set confirm its utility. Users targeting massive parallel compute workloads, such as AI training or scientific simulation, may find the MI455X's architecture appealing, but the lack of benchmark data means its actual performance remains unverified in this database. The verdict from recorded measurements is straightforward: the RX 7900 GRE delivers measurable results, while the MI455X does not.

Architecture Differences

The two accelerators come from different AMD architectures built for different roles. The MI455X uses CDNA 5.0 architecture on a 2 nm process from TSMC, with 320,000 million transistors on a die size of 2990 mm². This yields a transistor density of 107.0 million per mm². The RX 7900 GRE uses RDNA 3.0 architecture on a 5 nm process from the same foundry, with 57,700 million transistors on a die size of 529 mm², yielding a density of 109.1 million per mm². Despite the MI455X's larger node, the RX 7900 GRE actually has a slightly higher transistor density.

The MI455X's chip is designated "MI450 256CU," indicating a 256 compute unit design. It has 32768 shading units, 1024 TMUs, and 0 ROPs, with no ray tracing cores or tensor cores listed. Its FP32 throughput is 157.3 TFLOPS, and FP16 is also 157.3 TFLOPS at a 1:1 ratio. The RX 7900 GRE's chip is Navi 31, with 5120 shading units, 320 TMUs, 160 ROPs, and 80 ray tracing cores. Its FP32 is 45.98 TFLOPS, while FP16 reaches 91.96 TFLOPS at a 2:1 ratio, indicating a different compute ratio structure.

Memory architecture diverges sharply. The MI455X uses 432 GB of HBM4 memory on a 24576-bit bus, delivering 23.3 TB/s of bandwidth. The RX 7900 GRE uses 16 GB of GDDR6 memory on a 256-bit bus, delivering 576.0 GB/s. The MI455X's bus width is 96 times larger, and its bandwidth is over 40 times higher, reflecting its compute-optimized design. The MI455X has no display outputs, while the RX 7900 GRE includes HDMI 2.1a, DisplayPort 2.1, and USB Type-C.

Power requirements differ enormously. The MI455X has a TDP of 2300 W, uses no power connectors (likely integrated into its EAM Module slot), and suggests a 2700 W PSU. The RX 7900 GRE has a TDP of 260 W, uses 2x 8-pin power connectors, and suggests a 600 W PSU. The MI455X's power envelope is nearly nine times larger, reinforcing its data-center orientation. The RX 7900 GRE is a dual-slot card measuring 276 mm in length, 110 mm in height, and 51 mm in width, while the MI455X is an EAM Module with unspecified physical dimensions.

The MI455X uses PCIe 6.0 x16, while the RX 7900 GRE uses PCIe 4.0 x16. API support also differs: the MI455X lists N/A for DirectX, OpenGL, and Vulkan, whereas the RX 7900 GRE supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. Release dates are far apart: the MI455X launched on 2026-07-22, while the RX 7900 GRE launched on 2023-07-26. The RX 7900 GRE is marked as "Active" in production status, while the MI455X has no production status listed.

FAQ

Q: Which GPU has a higher benchmark score in the database?

A: The AMD Radeon RX 7900 GRE has an average benchmark score of 32456 and a percentile rank of 77. The AMD Instinct MI455X has an average score of 0 and a percentile rank of 50, with no recorded benchmark entries.

Q: How does the RX 7900 GRE compare to its nearest rivals?

A: The RX 7900 GRE is 0.2% ahead of the AMD FirePro S10000 (average score 32388) and 0.9% ahead of the AMD Radeon Pro 570X (average score 32176). It trails the AMD FirePro S9300 X2 by 0.3% (average score 32540) and the AMD Radeon RX 590 GME by 0.4% (average score 32601).

Q: What is the memory configuration of each card?

A: The MI455X has 432 GB of HBM4 memory on a 24576-bit bus with 23.3 TB/s bandwidth. The RX 7900 GRE has 16 GB of GDDR6 memory on a 256-bit bus with 576.0 GB/s bandwidth.

Q: Do both cards support modern APIs like DirectX 12?

A: No. The RX 7900 GRE supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. The MI455X lists N/A for DirectX, OpenGL, and Vulkan, indicating no graphics API support.

Q: What are the power requirements for each card?

A: The MI455X has a TDP of 2300 W and suggests a 2700 W PSU. The RX 7900 GRE has a TDP of 260 W and suggests a 600 W PSU.

Q: Which card has display outputs?

A: Only the RX 7900 GRE has display outputs: 1x HDMI 2.1a, 2x DisplayPort 2.1, and 1x USB Type-C. The MI455X has no outputs.

Where Each One Wins

The AMD Radeon RX 7900 GRE wins in every measurable benchmark category, since it is the only card with recorded scores. Its Passmark G3D score of 27089 and Geekbench OpenCL score of 175758 demonstrate strong graphics and compute performance. The card's 160 ROPs and 80 ray tracing cores give it dedicated hardware for rasterization and ray-traced workloads, making it suitable for gaming, content creation, and general-purpose GPU compute. Its DirectX 12 Ultimate support and Vulkan 1.4 compatibility ensure broad software coverage, while its 16 GB GDDR6 memory on a 256-bit bus provides adequate capacity and bandwidth for most consumer and prosumer tasks.

The AMD Instinct MI455X wins on raw hardware specifications, despite lacking benchmark data. Its 32768 shading units are 6.4 times the RX 7900 GRE's 5120, and its FP32 throughput of 157.3 TFLOPS is 3.4 times higher. The 432 GB HBM4 memory pool and 23.3 TB/s bandwidth dwarf the RX 7900 GRE's 16 GB and 576.0 GB/s, making the MI455X a candidate for memory-bound compute workloads like large model inference or scientific simulation. Its 24576-bit bus width and PCIe 6.0 interface also point toward high-throughput data movement. However, the absence of ROPs, display outputs, and graphics API support means it cannot render images or output video, limiting its use to non-visual compute tasks.

The power draw tells the same story. The MI455X's 2300 W TDP and 2700 W suggested PSU indicate a rack-mounted accelerator designed for dense compute nodes, while the RX 7900 GRE's 260 W TDP and 600 W PSU fit a standard desktop build. The RX 7900 GRE's dual-slot form factor and 2x 8-pin connectors are conventional, whereas the MI455X's EAM Module slot and lack of power connectors reflect a specialized mounting and power delivery system. The RX 7900 GRE also has a defined physical footprint of 276 mm by 110 mm by 51 mm, while the MI455X's dimensions are unrecorded.

In terms of production lifecycle, the RX 7900 GRE is active and has a successor listed as Navi IV, while the MI455X has no production status and no successor. The RX 7900 GRE also has a predecessor of Navi II, and the MI455X's predecessor is Radeon Instinct. The RX 7900 GRE's launch date of 2023-07-26 makes it a mature product, while the MI455X's 2026-07-22 release date suggests a newer design. Both are manufactured by AMD, but the MI455X's CDNA 5.0 architecture is compute-focused, while the RX 7900 GRE's RDNA 3.0 is graphics-focused.

Specification Differences

The two cards differ in nearly every specification field. The MI455X uses a 2 nm process with 320,000 million transistors on a 2990 mm² die, while the RX 7900 GRE uses a 5 nm process with 57,700 million transistors on a 529 mm² die. Transistor density is close: 107.0M per mm² for the MI455X versus 109.1M per mm² for the RX 7900 GRE. The MI455X's chip is "MI450 256CU," and the RX 7900 GRE's chip is "Navi 31."

Clocks differ significantly. The MI455X has a base clock of 1000 MHz and a boost clock of 2400 MHz, with no game clock listed. The RX 7900 GRE has a base clock of 1287 MHz, a boost clock of 2245 MHz, and a game clock of 1880 MHz. Memory clocks also differ: the MI455X runs at 1900 MHz (7.6 Gbps effective), while the RX 7900 GRE runs at 2250 MHz (18 Gbps effective).

Shading units, TMUs, and ROPs all differ. The MI455X has 32768 shading units, 1024 TMUs, and 0 ROPs. The RX 7900 GRE has 5120 shading units, 320 TMUs, and 160 ROPs. The MI455X has no ray tracing cores, while the RX 7900 GRE has 80. Pixel rate is 0 MPixel/s for the MI455X versus 359.2 GPixel/s for the RX 7900 GRE. Texture rate is 2,457.6 GTexel/s versus 718.4 GTexel/s. FP32 is 157.3 TFLOPS versus 45.98 TFLOPS, and FP16 is 157.3 TFLOPS (1:1) versus 91.96 TFLOPS (2:1).

Memory size, type, bus width, and bandwidth all differ: 432 GB HBM4 on 24576-bit with 23.3 TB/s versus 16 GB GDDR6 on 256-bit with 576.0 GB/s. TDP is 2300 W versus 260 W. Slot width is EAM Module versus dual-slot. Power connectors are none versus 2x 8-pin. Suggested PSU is 2700 W versus 600 W. Bus interface is PCIe 6.0 x16 versus PCIe 4.0 x16. Display outputs are none versus 1x HDMI 2.1a, 2x DisplayPort 2.1, 1x USB Type-C. API support is N/A for all three APIs versus DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4. Dimensions are unrecorded for the MI455X, while the RX 7900 GRE measures 276 mm by 110 mm by 51 mm. Release dates are 2026-07-22 versus 2023-07-26. The RX 7900 GRE has a launch MSRP of 549 USD, stated once here. Production status is unlisted for the MI455X and "Active" for the RX 7900 GRE.