AMD Instinct MI325X vs AMD Radeon Instinct MI300 Comparison

The Verdict

The AMD Instinct MI325X and AMD Radeon Instinct MI300 share the same Aqua Vanjaram chip, built on CDNA 3.0 architecture at TSMC's 5 nm node with 153,000 million transistors on a 1017 mm² die. Despite these commonalities, the MI325X is the more capable part across nearly every measurable specification. The MI325X doubles memory capacity to 256 GB of HBM3e versus 128 GB of HBM3 on the MI300, raises boost clock from 1700 MHz to 2100 MHz, and increases shading units from 14080 to 19456. The MI325X delivers 81.72 TFLOPS FP32 and 81.72 TFLOPS FP16 (1:1), while the MI300 produces 47.87 TFLOPS FP32 and 383.0 TFLOPS FP16 (8:1). The MI325X carries a 1000 W TDP with no power connectors (OAM Module), while the MI300 uses 600 W with 2x 8-pin connectors. The MI325X launched 2024-10-09, the MI300 launched 2023-01-03.

For workloads that need large memory footprints, the MI325X is the clear choice: 256 GB versus 128 GB doubles the capacity for models that exceed the MI300's limit. For raw FP32 throughput, the MI325X leads by a wide margin, 81.72 TFLOPS versus 47.87 TFLOPS, a 70.7% advantage. However, the MI300 has a substantial FP16 advantage in its native 8:1 mode: 383.0 TFLOPS versus 81.72 TFLOPS in 1:1 mode. Users needing maximum FP16 throughput for training or inference should select the MI300. Users needing memory capacity, FP32 compute, or higher boost clocks should select the MI325X.

Both cards sit at percentile 50 among all GPUs in the database, with no benchmark scores recorded, so the specification differences carry the analysis.

FAQ

Q: Which GPU has more memory?

A: The AMD Instinct MI325X has 256 GB of HBM3e memory. The AMD Radeon Instinct MI300 has 128 GB of HBM3. The MI325X doubles the capacity.

Q: Which GPU has higher memory bandwidth?

A: The MI300 has slightly higher memory bandwidth at 6.55 TB/s compared to 6.14 TB/s on the MI325X, despite the MI300 using HBM3 rather than HBM3e.

Q: How do the FP16 capabilities compare?

A: The MI300 delivers 383.0 TFLOPS FP16 in 8:1 mode, far exceeding the MI325X's 81.72 TFLOPS in 1:1 mode. The MI325X does not list an 8:1 mode in the database.

Q: What are the power requirements?

A: The MI325X has a TDP of 1000 W with a suggested PSU of 1400 W and no power connectors (OAM Module). The MI300 has a TDP of 600 W with a suggested PSU of 1000 W and uses 2x 8-pin connectors.

Q: Do both GPUs use the same chip?

A: Yes. Both use the Aqua Vanjaram chip on CDNA 3.0 architecture, fabricated by TSMC at 5 nm with 153,000 million transistors and a 1017 mm² die size.

Q: Which GPU has more shading units?

A: The MI325X has 19456 shading units, compared to 14080 on the MI300. The MI325X also has 1216 TMUs versus 880 TMUs.

Architecture Differences

Both accelerators are built on the same Aqua Vanjaram chip, using AMD's CDNA 3.0 architecture. The foundry is TSMC, and the process node is 5 nm for both. Transistor count is identical at 153,000 million, and die size is the same at 1017 mm², yielding a transistor density of 150.4M per mm² for both. The MI325X belongs to the Instinct (MIx) generation, while the MI300 belongs to the Radeon Instinct (MIx) generation.

The architecture differences manifest in implementation details. The MI325X has a boost clock of 2100 MHz versus 1700 MHz on the MI300, both with a 1000 MHz base clock. The MI325X uses HBM3e memory while the MI300 uses HBM3. The MI325X has 19456 shading units, 1216 TMUs, and 0 ROPs. The MI300 has 14080 shading units, 880 TMUs, and 0 ROPs. Neither has RT cores or tensor cores listed in the database.

The MI325X's FP16 implementation is 1:1, meaning it matches FP32 throughput at 81.72 TFLOPS. The MI300 uses an 8:1 FP16 mode, delivering 383.0 TFLOPS. This suggests a fundamentally different approach to FP16 execution between the two parts, even though both use the same underlying chip. The MI300's 8:1 ratio indicates a more aggressive FP16 path, while the MI325X emphasizes balanced FP32 and FP16 throughput.

Texture rate differs substantially: the MI325X achieves 2,553.6 GTexel/s versus 1,496.0 GTexel/s on the MI300. Pixel rate is listed as 0 MPixel/s for both, and neither has display outputs. API support is listed as N/A for the MI325X and null for the MI300 in DirectX, OpenGL, and Vulkan fields, consistent with compute-focused accelerators.

Specification Differences

The two GPUs differ in several key specification fields:

• Boost clock: MI325X at 2100 MHz, MI300 at 1700 MHz. Base clock is identical at 1000 MHz.
• Memory clock: MI325X runs at 1500 MHz (6 Gbps effective), MI300 at 1600 MHz (6.4 Gbps effective).
• Memory size: MI325X has 256 GB, MI300 has 128 GB.
• Memory type: MI325X uses HBM3e, MI300 uses HBM3.
• Memory bandwidth: MI325X at 6.14 TB/s, MI300 at 6.55 TB/s.
• Shading units: MI325X has 19456, MI300 has 14080.
• TMUs: MI325X has 1216, MI300 has 880.
• Texture rate: MI325X at 2,553.6 GTexel/s, MI300 at 1,496.0 GTexel/s.
• FP32 performance: MI325X at 81.72 TFLOPS, MI300 at 47.87 TFLOPS.
• FP16 performance: MI325X at 81.72 TFLOPS (1:1), MI300 at 383.0 TFLOPS (8:1).
• TDP: MI325X at 1000 W, MI300 at 600 W.
• Power connectors: MI325X has none (OAM Module), MI300 uses 2x 8-pin.
• Suggested PSU: MI325X at 1400 W, MI300 at 1000 W.
• Slot width: MI325X is an OAM Module, MI300 has no slot width listed.
• Dimensions: MI325X has no dimensions listed, MI300 is 267 mm (10.5 inches) long and 111 mm (4.4 inches) high.
• Release date: MI325X on 2024-10-09, MI300 on 2023-01-03.
• Predecessor: MI325X lists Radeon Instinct, MI300 lists FirePro Data Center.

Identical fields include process node (5 nm), foundry (TSMC), transistors (153,000 million), die size (1017 mm²), transistor density (150.4M / mm²), bus interface (PCIe 5.0 x16), bus width (8192 bit), ROPs (0), pixel rate (0 MPixel/s), display outputs (No outputs), and percentileVsAllGpus (50).

Head-to-Head Benchmarks

The database records no direct head-to-head benchmark results for these two accelerators, and neither has individual benchmark entries. The comparison therefore relies entirely on the specification-level data. The MI325X wins in several compute categories. In FP32, the MI325X delivers 81.72 TFLOPS versus 47.87 TFLOPS on the MI300, a 70.7% advantage. In texture rate, the MI325X reaches 2,553.6 GTexel/s versus 1,496.0 GTexel/s, a 70.7% advantage as well, consistent with the proportional increase in shading units and TMUs. The MI325X has 38.2% more shading units (19456 versus 14080) and 38.2% more TMUs (1216 versus 880).

The MI300 wins in FP16 throughput. Its 383.0 TFLOPS in 8:1 mode is 4.7 times the MI325X's 81.72 TFLOPS in 1:1 mode. This is the single largest performance differential between the two cards. The MI300 also has a slight memory bandwidth edge at 6.55 TB/s versus 6.14 TB/s, a 6.7% advantage, despite having half the memory capacity.

Boost clock favors the MI325X at 2100 MHz versus 1700 MHz, a 23.5% advantage. This higher clock contributes to the FP32 and texture rate leads. The MI300's memory clock is higher at 1600 MHz versus 1500 MHz, but the MI325X's HBM3e memory provides competitive bandwidth at 6.14 TB/s.

The MI325X doubles memory capacity from 128 GB to 256 GB, which is the largest absolute difference in the specification sheets. The MI300's bandwidth advantage is modest, while the MI325X's compute advantages in FP32 and texture rate are substantial. The MI300's FP16 advantage is decisive for workloads that can exploit 8:1 FP16 execution.

Where Each One Wins

The AMD Instinct MI325X wins in FP32 compute, texture throughput, shading resources, memory capacity, and boost clock. Its 81.72 TFLOPS FP32 performance suits workloads that rely on single-precision math, and its 19456 shading units with 1216 TMUs provide 2,553.6 GTexel/s of texture rate. The 256 GB HBM3e memory capacity accommodates larger models or datasets than the MI300's 128 GB. The 2100 MHz boost clock is the highest among the two. The MI325X requires a 1000 W TDP and a 1400 W suggested PSU, and it is an OAM Module with no power connectors.

The AMD Radeon Instinct MI300 wins in FP16 throughput with 383.0 TFLOPS in 8:1 mode, a 4.7x advantage over the MI325X's 1:1 FP16. This makes the MI300 the better choice for FP16-heavy workloads such as training or inference that can use the 8:1 path. The MI300 also has slightly higher memory bandwidth at 6.55 TB/s versus 6.14 TB/s, and it uses less power at 600 W TDP with a 1000 W suggested PSU. The MI300 is a PCIe 5.0 x16 card with 2x 8-pin power connectors and physical dimensions of 267 mm (10.5 inches) by 111 mm (4.4 inches), whereas the MI325X is an OAM Module with no listed dimensions.

Both cards carry the same percentileVsAllGpus of 50 and no recorded benchmark scores, so neither has demonstrated empirical performance data in the database. The MI325X targets capacity and FP32 compute, the MI300 targets FP16 throughput and power efficiency. Buyers with FP32 or capacity needs should prefer the MI325X. Buyers with FP16 8:1 workloads should prefer the MI300. The MI325X is the newer release, dated 2024-10-09, while the MI300 dates to 2023-01-03. The MI325X lists its predecessor as Radeon Instinct, and the MI300 lists its predecessor as FirePro Data Center.