AMD Instinct MI325X vs NVIDIA H100 CNX Comparison

Head-to-Head Benchmarks

The recorded data shows no direct head-to-head benchmark results between the AMD Instinct MI325X and the NVIDIA H100 CNX. Both entries in the database carry an average benchmark score of zero and hold the 50th percentile against all GPUs, indicating that aggregate performance measurements have not yet been populated for either accelerator. The wins counters for both parts are zero, confirming a tie in the absence of scored tests.

What can be compared directly are the peak compute figures listed in the specification records. The AMD Instinct MI325X delivers 81.72 TFLOPS of FP32 performance, while the NVIDIA H100 CNX delivers 53.84 TFLOPS. This places the AMD part 51.8% ahead in single-precision throughput. In FP16 compute, the picture reverses decisively in favor of the NVIDIA part. The H100 CNX lists 215.4 TFLOPS with a 4:1 ratio, while the MI325X lists 81.72 TFLOPS with a 1:1 ratio. The NVIDIA accelerator achieves 2.6 times the FP16 throughput of the AMD accelerator under those respective ratio definitions.

Memory bandwidth is another clear differentiator. The MI325X records 6.14 TB/s of bandwidth across an 8192-bit bus using HBM3e memory, whereas the H100 CNX records 2.04 TB/s across a 5120-bit bus using HBM2e. The AMD part delivers 3.0 times the memory bandwidth of the NVIDIA part. Texture throughput also favors the AMD hardware: 2,553.6 GTexel/s versus 841.3 GTexel/s, a 3.0-fold advantage. Pixel rate goes the other way, with the H100 CNX posting 44.28 GPixel/s against the MI325X's 0 MPixel/s, reflecting the AMD part's lack of ROP output capability.

Where Each One Wins

The AMD Instinct MI325X wins decisively in raw FP32 compute, memory capacity, memory bandwidth, and texture throughput. Its 256 GB of HBM3e memory dwarfs the 80 GB of HBM2e on the NVIDIA part, which matters for workloads where model weights or datasets must reside on the accelerator. The 6.14 TB/s bandwidth supports feeding 19,456 shading units and 1,216 texture mapping units without starvation. The 81.72 TFLOPS FP32 figure makes it the stronger choice for applications that rely on single-precision math.

The NVIDIA H100 CNX wins in FP16 compute, pixel throughput, and physical packaging practicality. Its 215.4 TFLOPS FP16 figure with a 4:1 ratio indicates a design tuned for mixed-precision and tensor-heavy workloads, despite the tensor core count of 456 being listed. The 44.28 GPixel/s pixel rate shows a functional ROP pipeline that the AMD part lacks entirely. The dual-slot form factor, 267 mm length, 111 mm height, and 350 W TDP allow installation in conventional server chassis with standard 8-pin EPS power. The AMD part requires an OAM module form factor with no power connectors listed and a 1000 W TDP, which imposes different system infrastructure demands.

Architecture Differences

The AMD Instinct MI325X uses the Aqua Vanjaram chip built on CDNA 3.0 architecture, manufactured on a 5 nm process at TSMC. The NVIDIA H100 CNX uses the GH100 chip built on Hopper architecture, also on a 5 nm process at TSMC. Both accelerators share the same process node and foundry, but the transistor counts diverge substantially. The MI325X packs 153,000 million transistors on a 1017 mm² die, yielding a transistor density of 150.4M per mm². The H100 CNX contains 80,000 million transistors on an 814 mm² die, with a density of 98.3M per mm². The AMD chip uses 1.9 times the transistor count and occupies 1.25 times the die area.

Memory technology differs completely. The MI325X uses HBM3e with 256 GB capacity, while the H100 CNX uses HBM2e with 80 GB capacity. The AMD memory clock runs at 1500 MHz with 6 Gbps effective, while the NVIDIA memory clock runs at 1593 MHz with 3.2 Gbps effective. Despite the lower clock, the AMD part achieves triple the bandwidth due to its wider 8192-bit bus versus 5120-bit.

The shading unit counts favor AMD: 19,456 versus 14,592. TMU counts also favor AMD: 1,216 versus 456. The NVIDIA part lists 456 tensor cores, while the AMD part lists no tensor core count. The MI325X lists zero ROPs, while the H100 CNX lists 24.

Clock behavior differs notably. The MI325X has a base clock of 1000 MHz and boost clock of 2100 MHz. The H100 CNX has a base clock of 690 MHz and boost clock of 1845 MHz. The AMD part runs 45% higher at base and 14% higher at boost. Power consumption scales accordingly: 1000 W TDP for the AMD part versus 350 W for the NVIDIA part.

API support also diverges. The MI325X lists DirectX, OpenGL, and Vulkan as N/A. The H100 CNX lists these fields as null. Neither accelerator provides display outputs.

Specification Differences

The two accelerators differ across nearly every measured specification field. Process node, foundry, bus interface, and generation class are the only shared traits: both use 5 nm TSMC fabrication and PCIe 5.0 x16 connectivity.

The AMD Instinct MI325X uses CDNA 3.0 architecture, while the NVIDIA H100 CNX uses Hopper. The AMD chip is Aqua Vanjaram; the NVIDIA chip is GH100. The AMD part has 153,000 million transistors versus 80,000 million. Die size is 1017 mm² versus 814 mm². Transistor density is 150.4M per mm² versus 98.3M per mm².

Base clock: 1000 MHz versus 690 MHz. Boost clock: 2100 MHz versus 1845 MHz. Memory clock: 1500 MHz (6 Gbps effective) versus 1593 MHz (3.2 Gbps effective). Memory size: 256 GB versus 80 GB. Memory type: HBM3e versus HBM2e. Bus width: 8192 bit versus 5120 bit. Bandwidth: 6.14 TB/s versus 2.04 TB/s.

Shading units: 19,456 versus 14,592. TMUs: 1,216 versus 456. ROPs: 0 versus 24. Tensor cores: not listed versus 456. Pixel rate: 0 MPixel/s versus 44.28 GPixel/s. Texture rate: 2,553.6 GTexel/s versus 841.3 GTexel/s. FP32: 81.72 TFLOPS versus 53.84 TFLOPS. FP16: 81.72 TFLOPS (1:1) versus 215.4 TFLOPS (4:1).

TDP: 1000 W versus 350 W. Slot width: OAM Module versus Dual-slot. Power connectors: none versus 8-pin EPS. Suggested PSU: 1400 W versus 750 W. Dimensions: not listed versus 267 mm by 111 mm. Release date: October 9, 2024 versus March 20, 2023. Production status: not listed versus Active. Predecessor: Radeon Instinct versus Server Ada. Successor: not listed versus Server Blackwell.

FAQ

Q: Which accelerator provides higher FP32 compute?

A: The AMD Instinct MI325X delivers 81.72 TFLOPS, which is 51.8% higher than the NVIDIA H100 CNX's 53.84 TFLOPS.

Q: How much memory bandwidth does each part offer?

A: The MI325X provides 6.14 TB/s via HBM3e on an 8192-bit bus. The H100 CNX provides 2.04 TB/s via HBM2e on a 5120-bit bus, making the AMD part 3.0 times faster.

Q: Which accelerator has the larger memory capacity?

A: The MI325X holds 256 GB of HBM3e, while the H100 CNX holds 80 GB of HBM2e. The AMD part offers 3.2 times the capacity.

Q: What is the FP16 performance difference?

A: The H100 CNX lists 215.4 TFLOPS with a 4:1 ratio, while the MI325X lists 81.72 TFLOPS with a 1:1 ratio. The NVIDIA part achieves 2.6 times the FP16 throughput.

Q: What are the power consumption figures?

A: The MI325X has a TDP of 1000 W with a suggested PSU of 1400 W. The H100 CNX has a TDP of 350 W with a suggested PSU of 750 W.

Q: What form factors do the two accelerators use?

A: The MI325X uses an OAM Module with no power connectors listed. The H100 CNX uses a Dual-slot design with an 8-pin EPS power connector and measures 267 mm by 111 mm.

The Verdict

The data points to a clear split by workload type. For FP32-intensive compute and memory-bound applications, the AMD Instinct MI325X is the stronger selection. Its 81.72 TFLOPS FP32 output, 256 GB HBM3e capacity, and 6.14 TB/s bandwidth provide 1.5 times the FP32 throughput and 3.0 times the memory bandwidth of the NVIDIA part. Workloads that require large in-memory datasets or wide data movement will benefit from the AMD accelerator's specifications.

For FP16-heavy mixed-precision workloads, the NVIDIA H100 CNX holds the advantage. Its 215.4 TFLOPS FP16 figure with a 4:1 ratio exceeds the AMD part by a factor of 2.6. The presence of 456 tensor cores, a 44.28 GPixel/s pixel rate, and a 350 W TDP make it a more power-efficient and physically practical option for systems with standard dual-slot PCIe infrastructure.

The MI325X demands 1000 W TDP and an OAM Module form factor, which restricts deployment to systems designed for that mounting style. The H100 CNX fits conventional dual-slot chassis with 8-pin EPS power and lists an Active production status. The release dates differ by about 19 months, with the AMD part arriving October 2024 and the NVIDIA part March 2023.

Choosing between them depends entirely on the compute pattern. FP32 and memory capacity favor the MI325X. FP16 and physical integration favor the H100 CNX. The database records no benchmark scores for either part, so the verdict rests on the specification differences alone.