AMD Instinct MI308X vs NVIDIA H800 SXM5 Comparison

Where Each One Wins

The AMD Instinct MI308X and NVIDIA H800 SXM5 serve different compute priorities based on their measured specifications. The MI308X leads in raw memory capacity, memory bandwidth, and FP32 throughput. It carries 192 GB of HBM3 versus 80 GB on the H800, and its 5.32 TB/s bandwidth outpaces the H800's 3.36 TB/s by a wide margin. For FP32 work, the MI308X delivers 81.72 TFLOPS compared to 59.30 TFLOPS, a substantial advantage for general compute loads that rely on single-precision arithmetic.

The H800 SXM5 wins decisively in FP16 throughput with 237.2 TFLOPS against the MI308X's 81.72 TFLOPS. This is a near-3x gap that favors the NVIDIA part for mixed-precision training and inference workloads. The H800 also has tensor cores, 528 of them, while the MI308X lists none. That structural difference makes the H800 better suited for matrix-heavy deep learning operations. The H800 also has a higher base clock at 1095 MHz versus 1000 MHz, though the MI308X boosts higher at 2100 MHz versus 1755 MHz.

Pixel rate is another clear split. The H800 has 24 ROPs and a 42.12 GPixel/s pixel rate, while the MI308X has zero ROPs and a 0 MPixel/s pixel rate. The MI308X is not designed for rasterization output at all. Texture rate favors the MI308X at 2,553.6 GTexel/s versus 926.6 GTexel/s, which reflects its larger TMU count of 1216 versus 528.

The use-case split is straightforward. The MI308X targets memory-bound and FP32-heavy workloads where capacity and bandwidth dominate. The H800 targets FP16 tensor-core workloads where mixed-precision matrix math is the primary bottleneck. Neither part is a general-purpose graphics card, and both lack display outputs.

Architecture Differences

The two accelerators use different architectures from different vendors. The MI308X is built on AMD's CDNA 3.0 architecture with the Aqua Vanjaram chip. The H800 uses NVIDIA's Hopper architecture with the GH100 chip. Both are fabricated on a 5 nm process at TSMC, but the silicon designs diverge sharply.

Transistor counts differ substantially. The MI308X packs 153,000 million transistors on a 1017 mm² die, yielding a transistor density of 150.4 million per square millimeter. The H800 has 80,000 million transistors on an 814 mm² die with a density of 98.3 million per square millimeter. The MI308X has nearly double the transistor count on a roughly 25% larger die.

Shading unit counts also differ. The MI308X has 19,456 shading units, while the H800 has 16,896. TMU counts are 1216 versus 528, a 2.3x advantage for AMD. The H800 has 24 ROPs; the MI308X has none. The H800 includes 528 tensor cores, and the MI308X has no tensor core field populated.

Memory architecture is a major differentiator. The MI308X uses an 8192-bit bus with 192 GB of HBM3. The H800 uses a 5120-bit bus with 80 GB of HBM3. Effective memory clock is nearly identical: 5.2 Gbps on the MI308X versus 5.3 Gbps on the H800. The bandwidth difference comes from the wider bus on the AMD part.

Clock behavior differs. The MI308X runs at a 1000 MHz base and 2100 MHz boost. The H800 runs at 1095 MHz base and 1755 MHz boost. The FP16 throughput figures reveal the architectural intent: the MI308X reports 81.72 TFLOPS at a 1:1 ratio to FP32, meaning it does not accelerate FP16 beyond its FP32 rate. The H800 reports 237.2 TFLOPS at a 4:1 ratio, meaning its tensor cores deliver four times the FP32 rate for FP16.

Power delivery and form factor also differ. The MI308X is an OAM module with no power connectors and a 750 W TDP. The H800 is an SXM module with an 8-pin EPS connector and a 700 W TDP. The suggested PSU ratings are 1150 W for the MI308X and 1100 W for the H800. Both use PCIe 5.0 x16 interfaces.

Release dates are available. The H800 launched on March 20, 2023, and the MI308X launched on December 5, 2023. The H800 lists a production status of Active, while the MI308X has no production status recorded. The H800 has a successor (Server Blackwell), and the MI308X has none listed.

FAQ

Q: Which accelerator has more memory?

A: The MI308X has 192 GB of HBM3, which is 112 GB more than the H800's 80 GB. The MI308X also has a wider 8192-bit bus versus 5120-bit on the H800.

Q: Which part delivers higher FP16 throughput?

A: The H800 SXM5 delivers 237.2 TFLOPS FP16, nearly three times the MI308X's 81.72 TFLOPS. The H800 achieves this through its 528 tensor cores and a 4:1 FP16-to-FP32 ratio.

Q: Do either of these cards support display output?

A: No. Both the MI308X and H800 have no display outputs. They are compute accelerators designed for server deployments, not graphics rendering.

Q: What is the power consumption difference?

A: The MI308X has a 750 W TDP, and the H800 has a 700 W TDP. The suggested PSU is 1150 W for the MI308X and 1100 W for the H800.

Q: Which architecture does each use?

A: The MI308X uses AMD's CDNA 3.0 architecture with the Aqua Vanjaram chip. The H800 uses NVIDIA's Hopper architecture with the GH100 chip. Both are fabricated on a 5 nm TSMC process.

Q: How do the clock speeds compare?

A: The MI308X has a 1000 MHz base clock and a 2100 MHz boost clock. The H800 has a 1095 MHz base clock and a 1755 MHz boost clock. The H800 starts higher but the MI308X boosts significantly higher.

Specification Differences

The two accelerators differ across nearly every measurable specification. The MI308X uses the Aqua Vanjaram chip with CDNA 3.0 architecture, while the H800 uses the GH100 chip with Hopper architecture. Transistor counts are 153,000 million versus 80,000 million. Die size is 1017 mm² versus 814 mm². Transistor density is 150.4 million per mm² versus 98.3 million per mm².

Clock speeds differ in both base and boost. Base is 1000 MHz on the MI308X and 1095 MHz on the H800. Boost is 2100 MHz versus 1755 MHz. Memory clock is 1300 MHz with 5.2 Gbps effective on the MI308X, and 1313 MHz with 5.3 Gbps effective on the H800.

Memory capacity is 192 GB versus 80 GB. Bus width is 8192 bit versus 5120 bit. Bandwidth is 5.32 TB/s versus 3.36 TB/s. Shading units are 19,456 versus 16,896. TMUs are 1216 versus 528. ROPs are 0 versus 24. Tensor cores are absent on the MI308X and 528 on the H800.

Pixel rate is 0 MPixel/s on the MI308X and 42.12 GPixel/s on the H800. Texture rate is 2,553.6 GTexel/s versus 926.6 GTexel/s. FP32 is 81.72 TFLOPS versus 59.30 TFLOPS. FP16 is 81.72 TFLOPS (1:1) versus 237.2 TFLOPS (4:1).

TDP is 750 W versus 700 W. Slot width is OAM Module versus SXM Module. Power connectors are none versus 8-pin EPS. Suggested PSU is 1150 W versus 1100 W. Bus interface is PCIe 5.0 x16 for both. Display outputs are none for both.

The H800 has an Active production status, while the MI308X has none recorded. Release dates are March 20, 2023, for the H800 and December 5, 2023, for the MI308X. The H800 lists a predecessor (Server Ada) and successor (Server Blackwell), while the MI308X lists Radeon Instinct as a predecessor and no successor.

Head-to-Head Benchmarks

The recorded data shows no head-to-head benchmark entries, but the specification sheets provide direct comparisons for key metrics. The largest win for the MI308X is memory bandwidth. At 5.32 TB/s, it holds a 58% advantage over the H800's 3.36 TB/s. This is driven by the 8192-bit bus, which is 60% wider than the H800's 5120-bit bus.

Memory capacity is the second major win for the MI308X. Its 192 GB is 2.4 times the H800's 80 GB. This difference matters for large model footprints that must reside in high-bandwidth memory.

FP32 throughput favors the MI308X at 81.72 TFLOPS versus 59.30 TFLOPS, a 38% advantage. Texture rate also favors the MI308X at 2,553.6 GTexel/s versus 926.6 GTexel/s, a 2.8x gap.

The H800's biggest win is FP16 throughput. At 237.2 TFLOPS, it is 2.9 times the MI308X's 81.72 TFLOPS. This is the most dramatic single-metric difference between the two parts. The tensor core count of 528 on the H800, with none listed on the MI308X, explains this result.

Pixel rate is another H800 advantage. The H800 delivers 42.12 GPixel/s, while the MI308X records 0 MPixel/s. This reflects the MI308X's lack of ROPs, making it unsuitable for any rasterization output.

Boost clock favors the MI308X at 2100 MHz versus 1755 MHz, a 20% higher ceiling. Base clock favors the H800 at 1095 MHz versus 1000 MHz, though the boost advantage matters more for sustained workloads. Texture rate and FP32 show consistent AMD leads. FP16 and pixel rate show consistent NVIDIA leads.

The MI308X has a higher transistor density at 150.4 million per mm² versus 98.3 million per mm². The die size difference is 1017 mm² versus 814 mm². Power consumption is close, with the MI308X at 750 W and the H800 at 700 W, a 50 W gap. Both parts require substantial power delivery infrastructure, with suggested PSU ratings of 1150 W and 1100 W respectively.

The release timing shows the H800 arrived first in March 2023, and the MI308X followed in December 2023. Both use the PCIe 5.0 x16 interface and HBM3 memory. The MI308X uses no power connectors, relying on the OAM module's baseboard power, while the H800 uses an 8-pin EPS connector on its SXM module.

The benchmark data indicates a clear division of strengths. The MI308X dominates in memory-centric and FP32-centric metrics. The H800 dominates in FP16 tensor-core throughput and pixel output. Neither part covers the other's strengths, making the choice dependent on the workload mix.