AMD Instinct MI455X vs NVIDIA B200 SXM6 Comparison

Where Each One Wins

The recorded data presents a clear division of strengths between the AMD Instinct MI455X and the NVIDIA B200 SXM6. The AMD Instinct MI455X wins decisively on raw compute throughput, memory capacity, and memory bandwidth. The NVIDIA B200 SXM6 counters with operational efficiency, a higher transistor density, and a substantially lower power envelope.

In compute-heavy workloads, the AMD Instinct MI455X delivers 157.3 TFLOPS for both FP32 and FP16 operations, more than double the 69.34 TFLOPS recorded for the NVIDIA B200 SXM6 in the same precisions. This 2.27x advantage in raw floating-point throughput positions the MI455X as the dominant option for dense matrix mathematics and high-throughput parallel processing.

Memory capacity heavily favors the AMD part. The MI455X carries 432 GB of HBM4 memory, while the B200 SXM6 is equipped with 180 GB of HBM3e. The AMD solution also leads in bandwidth at 23.3 TB/s versus 8.19 TB/s for NVIDIA, a 2.84x margin. For workloads that require massive datasets resident on the GPU, the MI455X offers more than double the capacity and nearly triple the memory bandwidth.

The NVIDIA B200 SXM6 wins on efficiency metrics. Its 1000 W TDP is less than half of the 2300 W TDP recorded for the AMD MI455X. The B200 also achieves a higher transistor density at 127.8 million transistors per square millimeter, compared to 107.0 million for the AMD chip, despite using a 5 nm process node versus AMD's 2 nm node. The B200's pixel rate of 43.92 GPixel/s, while modest, is infinitely higher than the 0 MPixel/s recorded for the MI455X, which has no ROPs configured.

The benchmark database shows no recorded wins for either product in head-to-head testing, as the `headToHeadBenchmarks` array is empty. Both products sit at the 50th percentile among all GPUs in the database, with average benchmark scores of zero. The absence of benchmark data means the analysis relies on the architectural and specification records.

FAQ

Q: Which GPU has more memory?

A: The AMD Instinct MI455X has 432 GB of HBM4 memory, while the NVIDIA B200 SXM6 has 180 GB of HBM3e. The AMD part provides 2.4x the memory capacity.

Q: What is the memory bandwidth difference?

A: The MI455X delivers 23.3 TB/s of bandwidth across a 24576-bit bus. The B200 SXM6 delivers 8.19 TB/s across an 8192-bit bus. The AMD GPU offers 2.84x the bandwidth.

Q: How do the power requirements compare?

A: The AMD Instinct MI455X has a 2300 W TDP with a suggested PSU of 2700 W. The NVIDIA B200 SXM6 has a 1000 W TDP with a suggested PSU of 1400 W. The NVIDIA part consumes less than half the power.

Q: Which GPU has higher FP32 performance?

A: The AMD Instinct MI455X records 157.3 TFLOPS FP32, while the NVIDIA B200 SXM6 records 69.34 TFLOPS FP32. The AMD GPU is 2.27x faster in this metric.

Q: What process nodes are used?

A: The AMD Instinct MI455X uses a 2 nm process at TSMC. The NVIDIA B200 SXM6 uses a 5 nm process at TSMC. Despite the larger node, the B200 achieves a higher transistor density.

Q: What is the release timeline for these products?

A: The NVIDIA B200 SXM6 was released on 2024-10-31 and is marked as Active in production. The AMD Instinct MI455X has a release date of 2026-07-22. The B200's predecessor is Server Hopper, and its successor is Server Rubin.

Head-to-Head Benchmarks

The benchmark database contains no recorded head-to-head benchmark scores for these two accelerators. The `headToHeadBenchmarks` array is empty, and wins for each product are zero. Consequently, the comparison must derive from the specification-level metrics recorded in the database.

The largest advantage for the AMD Instinct MI455X appears in FP32 throughput. The MI455X records 157.3 TFLOPS, while the B200 SXM6 records 69.34 TFLOPS. This represents a 87.9 TFLOPS raw difference, meaning the AMD part delivers 2.27x the floating-point compute of the NVIDIA part. The same ratio applies to FP16 performance, as both products list a 1:1 ratio between FP16 and FP32. This consistency suggests the MI455X is optimized for uniform throughput across precision formats.

Memory bandwidth shows an even wider gap. The MI455X's 23.3 TB/s exceeds the B200's 8.19 TB/s by 15.11 TB/s, a 2.84x multiplier. The bus width difference is equally stark: 24576 bits for AMD versus 8192 bits for NVIDIA. The MI455X's memory clock runs at 1900 MHz with 7.6 Gbps effective data rate, while the B200 runs at 2000 MHz with 8 Gbps effective. The AMD part compensates for its slightly lower memory clock with a tripled bus width.

The NVIDIA B200 SXM6 wins decisively on power efficiency. At 1000 W TDP, the B200 consumes 1300 W less than the MI455X's 2300 W TDP. When considering compute per watt, the B200 delivers 69.34 TFLOPS per 1000 W, or 0.069 TFLOPS per watt. The MI455X delivers 157.3 TFLOPS per 2300 W, or 0.068 TFLOPS per watt. The two are nearly identical in efficiency per watt, but the B200 achieves this parity at a much lower absolute power draw.

Pixel rate also favors NVIDIA. The B200 SXM6 records 43.92 GPixel/s with 24 ROPs, while the MI455X records 0 MPixel/s with 0 ROPs. This indicates the AMD part is not designed for rasterization workloads, while the NVIDIA part retains some display and pixel processing capability despite having no display outputs.

Texture rate favors AMD at 2,457.6 GTexel/s versus 1,083.4 GTexel/s for NVIDIA, a 2.27x advantage that mirrors the FP32 ratio and reflects the MI455X's 1024 TMUs versus the B200's 592 TMUs.

Specification Differences

The two accelerators diverge across nearly every recorded specification. The AMD Instinct MI455X uses the MI450 256CU chip with CDNA 5.0 architecture, while the NVIDIA B200 SXM6 uses the GB100 chip with Blackwell architecture. The MI455X belongs to the Instinct (MIx) generation, while the B200 belongs to the Server Blackwell (Bxx) generation.

Process technology differs significantly. AMD uses a 2 nm node at TSMC with 320,000 million transistors on a 2990 mm² die. NVIDIA uses a 5 nm node at TSMC with 208,000 million transistors on a 1628 mm² die. Despite the smaller node, AMD's transistor density is lower at 107.0 million per mm² versus 127.8 million per mm² for NVIDIA.

Clock speeds show a notable divergence. The MI455X has a base clock of 1000 MHz and a boost clock of 2400 MHz. The B200 SXM6 has a base clock of 120 MHz and a boost clock of 1830 MHz. The AMD part runs significantly faster at both ends of the clock spectrum.

Memory configuration differs completely. The MI455X uses 432 GB of HBM4 with a 24576-bit bus and 23.3 TB/s bandwidth. The B200 uses 180 GB of HBM3e with an 8192-bit bus and 8.19 TB/s bandwidth. Memory clocks are close: 1900 MHz for AMD versus 2000 MHz for NVIDIA.

Shader resources favor AMD substantially. The MI455X has 32,768 shading units, 1024 TMUs, and 0 ROPs. The B200 has 18,944 shading units, 592 TMUs, and 24 ROPs. The B200 also includes 592 tensor cores, while the MI455X records no tensor core count. The B200's pixel rate is 43.92 GPixel/s, while the MI455X records 0 MPixel/s.

Power and physical specifications differ markedly. The MI455X has a 2300 W TDP with a suggested PSU of 2700 W, uses an EAM Module slot width, and lists no power connectors. The B200 has a 1000 W TDP with a suggested PSU of 1400 W, uses an SXM Module slot width, and lists no power connector data. Both use PCIe 6.0 x16 interfaces and have no display outputs.

Release dates are separated by roughly two years. The B200 launched on 2024-10-31 and is production Active. The MI455X has a release date of 2026-07-22 with no production status recorded. The B200 has a recorded launch MSRP of 34,999 USD.

Architecture Differences

The AMD Instinct MI455X uses the CDNA 5.0 architecture on the MI450 256CU chip. This architecture is designed for compute acceleration with no display outputs and no DirectX, OpenGL, or Vulkan API support. The MI455X has no ROPs and records 0 MPixel/s pixel rate, confirming a pure compute design.

The NVIDIA B200 SXM6 uses the Blackwell architecture on the GB100 chip. Blackwell retains some rasterization capability, evidenced by its 24 ROPs and 43.92 GPixel/s pixel rate, though it also lacks display outputs and API support. The B200 includes 592 tensor cores, which are not listed for the MI455X.

Transistor counts differ by 112,000 million, with the MI455X at 320,000 million and the B200 at 208,000 million. The MI455X's die is 1362 mm² larger at 2990 mm² versus 1628 mm². This larger die accommodates more compute units but results in lower transistor density: 107.0 million per mm² versus 127.8 million per mm² for the B200.

The memory architecture reflects different design priorities. HBM4 in the MI455X provides 432 GB capacity with a 24576-bit bus. HBM3e in the B200 provides 180 GB with an 8192-bit bus. The AMD part uses a wider bus to achieve higher bandwidth despite a slightly lower memory clock.

The MI455X's boost clock of 2400 MHz is 570 MHz higher than the B200's 1830 MHz boost. The base clocks differ even more dramatically: 1000 MHz for AMD versus 120 MHz for NVIDIA. These clock differences suggest the AMD architecture prioritizes sustained high-frequency operation, while the NVIDIA architecture relies on a lower base clock with boost behavior.

The 2 nm process node for AMD versus 5 nm for NVIDIA represents a two-generation process advantage for the MI455X. However, the B200 achieves higher transistor density on the older node, indicating a more compact transistor layout or different design methodology.

The Verdict

The data records two accelerators with opposing design philosophies. The AMD Instinct MI455X is built for maximum compute throughput and memory capacity. Its 157.3 TFLOPS FP32 performance, 432 GB of HBM4 memory, and 23.3 TB/s bandwidth make it the clear choice for workloads that saturate memory and compute resources simultaneously.

The NVIDIA B200 SXM6 is designed for efficiency and density. At 1000 W TDP with a 1400 W suggested PSU, it consumes less than half the power of the MI455X while delivering 69.34 TFLOPS FP32 and 8.19 TB/s bandwidth. Its 180 GB of HBM3e memory, while smaller, still provides substantial capacity for most inference and training workloads.

Users who require maximum performance per socket should select the AMD Instinct MI455X based on the recorded data. The 2.27x FP32 advantage, 2.4x memory capacity advantage, and 2.84x bandwidth advantage are decisive for compute-bound applications. The trade-off is a 2300 W TDP and a 2700 W suggested PSU, which demands significant power and cooling infrastructure.

Users who prioritize power efficiency, denser deployments, or tensor core acceleration should select the NVIDIA B200 SXM6. Its 1000 W TDP enables higher accelerator density per rack, its 592 tensor cores provide dedicated matrix math capability, and its Active production status indicates current availability. The recorded launch MSRP of 34,999 USD provides a reference point for procurement planning.

The benchmark database records no head-to-head measurements, so the analysis rests entirely on specification-level data. The MI455X's release date of 2026-07-22 suggests it is a future product, while the B200's 2024-10-31 release and Active status indicate it is currently deployed. The MI455X's predecessor is Radeon Instinct, while the B200's predecessor is Server Hopper and its successor is Server Rubin.

The choice between these accelerators depends on whether the workload favors raw throughput or operational efficiency. The MI455X wins every compute and memory metric recorded. The B200 wins every efficiency and density metric recorded. Neither product records display outputs or consumer API support, confirming both are purpose-built for datacenter acceleration.