AMD Instinct MI308X vs AMD Instinct MI325X Comparison

FAQ

Q: What are the core compute specifications of the AMD Instinct MI308X and AMD Instinct MI325X?

A: Both accelerators are built on the same CDNA 3.0 architecture using the Aqua Vanjaram chip. Each has 19,456 shading units, 1,216 texture mapping units, and 0 raster output pipelines. Both deliver 81.72 TFLOPS for FP32 and FP16 (1:1) operations.

Q: How do the memory configurations differ between the two cards?

A: The MI308X uses 192 GB of HBM3 memory with a bandwidth of 5.32 TB/s, while the MI325X uses 256 GB of HBM3e memory with a bandwidth of 6.14 TB/s. Both have an 8192-bit memory bus width.

Q: What are the clock speed differences?

A: Both cards have a base clock of 1000 MHz and a boost clock of 2100 MHz. The memory clock differs: the MI308X runs at 1300 MHz (5.2 Gbps effective), while the MI325X runs at 1500 MHz (6 Gbps effective).

Q: Are there any differences in power requirements?

A: Yes. The MI308X has a TDP of 750 W and a suggested PSU of 1150 W. The MI325X has a TDP of 1000 W and a suggested PSU of 1400 W. Both use OAM Module slot width and have no power connectors listed.

Q: When were these accelerators released?

A: The MI308X was released on 2023-12-05, and the MI325X was released on 2024-10-09. Both belong to the Instinct (MIx) generation and have the Radeon Instinct as their predecessor.

Q: Do these cards support display outputs or standard graphics APIs?

A: Neither card has display outputs. Both have N/A values for DirectX, OpenGL, and Vulkan support. They are compute-focused accelerators.

Architecture Differences

Both the AMD Instinct MI308X and AMD Instinct MI325X share the same fundamental architecture. They use the Aqua Vanjaram chip built on CDNA 3.0 architecture, manufactured by TSMC on a 5 nm process node. The transistor count is identical at 153,000 million, and the die size is the same at 1017 mm². The transistor density works out to 150.4M per mm² on both parts.

The compute architecture is unchanged between the two. Each card has 19,456 shading units and 1,216 TMUs. There are no raster output pipelines (0 ROPs), no ray tracing cores, and no tensor cores listed in the database. The pixel rate is 0 MPixel/s on both, reflecting their purpose as compute accelerators rather than graphics cards. The texture rate is identical at 2,553.6 GTexel/s, and the FP32 and FP16 throughput matches at 81.72 TFLOPS with a 1:1 ratio.

The key architectural difference lies in the memory subsystem. The MI308X pairs its compute with 192 GB of HBM3 memory, while the MI325X upgrades to 256 GB of HBM3e memory. The bus width remains 8192 bits on both, but the memory clock increases from 1300 MHz (5.2 Gbps effective) on the MI308X to 1500 MHz (6 Gbps effective) on the MI325X. This yields a bandwidth improvement from 5.32 TB/s to 6.14 TB/s.

The power delivery architecture also differs. The MI308X has a TDP of 750 W with a suggested PSU of 1150 W. The MI325X has a TDP of 1000 W with a suggested PSU of 1400 W. Both are OAM Modules with no power connectors listed, and both use a PCIe 5.0 x16 bus interface.

The release timeline shows the MI308X arriving on 2023-12-05, with the MI325X following on 2024-10-09. Both share the same predecessor, the Radeon Instinct, and neither has a listed successor in the database.

Head-to-Head Benchmarks

The database contains no recorded benchmark scores for either the AMD Instinct MI308X or the AMD Instinct MI325X. The benchmark arrays are empty for both cards, and the head-to-head benchmark results show no entries. This means there are no measured performance deltas, no win counts, and no percentage differences to report between the two accelerators.

The average benchmark score is 0 for both cards, and the percentile versus all GPUs is 50 for each. The nearest rivals lists are also empty, so there are no external comparison points available in the database.

What can be compared directly from the recorded specifications is the memory performance. The MI325X offers 64 GB more memory capacity than the MI308X (256 GB versus 192 GB). The memory bandwidth advantage for the MI325X is 0.82 TB/s higher (6.14 TB/s versus 5.32 TB/s), which represents a meaningful increase for memory-bound workloads. The effective memory data rate rises from 5.2 Gbps to 6 Gbps.

Compute throughput shows no difference. Both cards deliver 81.72 TFLOPS in FP32 and FP16 operations. The texture rate of 2,553.6 GTexel/s is identical. The shading unit count and TMU count match exactly. For workloads that are limited by raw compute rather than memory, the two cards should perform equivalently according to the specification data.

The power envelope is where the specifications diverge significantly. The MI325X requires 250 W more TDP (1000 W versus 750 W) and a suggested PSU that is 250 W higher (1400 W versus 1150 W). This additional power budget corresponds with the faster memory clock and larger memory capacity.

Specification Differences

The following fields differ between the AMD Instinct MI308X and the AMD Instinct MI325X:

• Memory size: 192 GB on the MI308X, 256 GB on the MI325X
• Memory type: HBM3 on the MI308X, HBM3e on the MI325X
• Memory clock: 1300 MHz (5.2 Gbps effective) on the MI308X, 1500 MHz (6 Gbps effective) on the MI325X
• Memory bandwidth: 5.32 TB/s on the MI308X, 6.14 TB/s on the MI325X
• TDP: 750 W on the MI308X, 1000 W on the MI325X
• Suggested PSU: 1150 W on the MI308X, 1400 W on the MI325X
• Release date: 2023-12-05 for the MI308X, 2024-10-09 for the MI325X

All other specification fields are identical between the two cards. This includes the chip (Aqua Vanjaram), architecture (CDNA 3.0), process node (5 nm), foundry (TSMC), transistor count (153,000 million), die size (1017 mm²), transistor density (150.4M / mm²), base clock (1000 MHz), boost clock (2100 MHz), memory bus width (8192 bit), shading units (19,456), TMUs (1,216), ROPs (0), pixel rate (0 MPixel/s), texture rate (2,553.6 GTexel/s), FP32 performance (81.72 TFLOPS), FP16 performance (81.72 TFLOPS), slot width (OAM Module), power connectors (None), bus interface (PCIe 5.0 x16), display outputs (No outputs), API support (N/A for DirectX, OpenGL, Vulkan), and predecessor (Radeon Instinct).

The Verdict

The data shows two accelerators that are compute-identical but memory-different. The AMD Instinct MI308X and AMD Instinct MI325X share the same chip, the same architecture, the same clock speeds, and the same FP32 and FP16 throughput. Any workload that is purely compute-bound should see matching performance from both cards according to the specifications.

The MI325X distinguishes itself through the memory subsystem. It offers 64 GB more capacity and 0.82 TB/s more bandwidth than the MI308X. This makes it the better choice for models or datasets that exceed the 192 GB capacity of the MI308X, or for workloads where memory bandwidth is the limiting factor. The memory clock increase from 1300 MHz to 1500 MHz and the switch from HBM3 to HBM3e are the enablers of this improvement.

The MI308X, released earlier on 2023-12-05, carries a lower power requirement. Its TDP of 750 W and suggested PSU of 1150 W are both 250 W lower than the MI325X figures. For systems with power constraints or existing power delivery limitations, the MI308X is the more accommodating option. The compute performance is unchanged, so the trade-off is memory capability versus power budget.

The MI325X, released on 2024-10-09, represents the higher-end option in this comparison. Its 1000 W TDP and 1400 W suggested PSU reflect the additional memory resources. The 256 GB capacity and 6.14 TB/s bandwidth are the largest advantages in the recorded data.

Neither card has benchmark scores in the database, so the verdict rests entirely on the specification differences. The MI325X wins on memory capacity, memory bandwidth, and memory technology. The MI308X wins on lower power consumption and a lower suggested PSU requirement. Compute performance is a tie.

Where Each One Wins

AMD Instinct MI308X wins in power-constrained deployments. The 750 W TDP and 1150 W suggested PSU make it the lighter power load. Systems that cannot supply or cool a 1000 W component can still accommodate the MI308X. The compute performance is identical to the MI325X, so for workloads that fit within 192 GB of HBM3 memory and do not require the extra bandwidth, the MI308X delivers the same FP32 and FP16 throughput with less power draw.

AMD Instinct MI325X wins in memory-capacity-bound scenarios. The 256 GB of HBM3e memory is 64 GB larger than the 192 GB HBM3 on the MI308X. Workloads that need to hold larger models, bigger batch sizes, or more data in memory will benefit from the additional capacity. The 6.14 TB/s bandwidth is also higher than the 5.32 TB/s available on the MI308X, which helps memory-intensive operations.

The MI325X wins on raw memory throughput. The effective memory data rate of 6 Gbps versus 5.2 Gbps, combined with the higher memory clock of 1500 MHz versus 1300 MHz, gives the MI325X a clear bandwidth advantage. The 8192-bit bus width is the same on both cards, so the bandwidth difference comes entirely from the faster memory clock and the HBM3e memory type.

The MI308X wins on integration ease. The lower TDP and suggested PSU mean less demand on system power delivery and thermal management. The identical compute specifications mean no loss in FP32 or FP16 performance. For builders who already have power infrastructure sized for lower-wattage accelerators, the MI308X avoids the need for upgrades.

Both cards win on compute consistency. The shading units, TMUs, texture rate, and FP32/FP16 TFLOPS are exactly the same. There is no scenario in the recorded data where one card outperforms the other in raw compute throughput. The choice between them comes down to memory resources and power requirements, not processing capability.