AMD Instinct MI350X vs AMD Instinct MI355X Comparison

FAQ

Q: What is the primary difference between the AMD Instinct MI350X and the AMD Instinct MI355X?

A: Both cards use the same MI350 256CU chip, CDNA 4.0 architecture, 3 nm process node, and 288 GB of HBM3e memory with an 8192-bit bus. The key differences are the boost clock, texture rate, FP32/FP16 throughput, TDP, and suggested PSU.

Q: How much faster is the MI355X in raw compute performance?

A: The MI355X delivers 78.64 TFLOPS FP32 and FP16, while the MI350X delivers 72.09 TFLOPS in both. That is a difference of 6.55 TFLOPS, which translates to roughly 9% higher throughput for the MI355X.

Q: Do the two cards have identical memory specifications?

A: Yes. Both have 288 GB of HBM3e memory, a 8192-bit bus width, and 8.19 TB/s of bandwidth. The memory clock is also the same at 2000 MHz with 8 Gbps effective speed.

Q: Are there any differences in physical dimensions or mounting?

A: No. Both are OAM Modules with the same length of 102 mm (4 inches) and width of 165 mm (6.5 inches). Neither has display outputs, and both use PCIe 5.0 x16 as the bus interface.

Q: What are the power requirement differences?

A: The MI350X has a TDP of 1000 W and a suggested PSU of 1400 W. The MI355X has a TDP of 1400 W and a suggested PSU of 1800 W. The MI355X requires 400 W more in TDP and 400 W more in suggested PSU.

Q: What is the transistor count and die size for each?

A: Both cards have 185,000 million transistors on a 2380 mm² die, resulting in a transistor density of 77.7M per mm². The foundry is TSMC for both.

The Verdict

The data shows two accelerators built on the same MI350 256CU chip, CDNA 4.0 architecture, and identical memory subsystems. The MI355X is the higher-clocked variant, with a boost clock of 2400 MHz versus 2200 MHz on the MI350X. This yields a texture rate of 2457.6 GTexel/s versus 2252.8 GTexel/s, and FP32/FP16 throughput of 78.64 TFLOPS versus 72.09 TFLOPS.

The MI350X is the lower-power option, with a TDP of 1000 W and a suggested PSU of 1400 W. The MI355X demands 1400 W TDP and an 1800 W suggested PSU. For installations where power delivery and cooling capacity are constrained, the MI350X fits more readily. For maximum compute throughput per card, the MI355X provides the higher numbers.

Both cards share the same release date of 2025-06-11, the same predecessor (Radeon Instinct), the same 3 nm process, and the same 288 GB memory pool. The choice comes down to whether the extra 6.55 TFLOPS of FP32/FP16 performance justifies the additional 400 W of TDP and the larger PSU recommendation. Benchmark scores are not recorded in the database for either card, and both sit at the 50th percentile among all GPUs, so the verdict rests entirely on the clock, throughput, and power figures.

Head-to-Head Benchmarks

The database contains no recorded benchmark scores for either card, so a direct comparison of measured performance results is not possible. Instead, the head-to-head comparison derives from the recorded specifications that determine compute throughput.

The MI355X wins on boost clock, delivering 2400 MHz versus 2200 MHz on the MI350X. This 200 MHz advantage directly drives the texture rate difference. The MI355X reaches 2457.6 GTexel/s, while the MI350X produces 2252.8 GTexel/s, a gap of 204.8 GTexel/s. In FP32 compute, the MI355X outputs 78.64 TFLOPS against the MI350X's 72.09 TFLOPS, a 6.55 TFLOPS advantage. The FP16 figures match the FP32 figures exactly for both cards, with a 1:1 ratio, meaning the same 6.55 TFLOPS lead applies to half-precision workloads.

The MI350X wins on power efficiency. Its TDP of 1000 W is 400 W lower than the MI355X's 1400 W. With a smaller suggested PSU of 1400 W versus 1800 W, the MI350X requires less infrastructure per card. Pixel rate is identical at 0 MPixel/s for both, and the ROP count is 0 for both, reflecting their non-rendering compute-focused design.

The memory subsystem shows no difference. Both cards use 288 GB of HBM3e, an 8192-bit bus, and 8.19 TB/s bandwidth. The memory clock is 2000 MHz with 8 Gbps effective speed on both. Shading units are 16384 on both, and TMUs are 1024 on both. The base clock is also the same at 1000 MHz.

Specification Differences

The two cards differ in four recorded specification areas. First, the boost clock: the MI355X runs at 2400 MHz, the MI350X at 2200 MHz. Second, the texture rate: the MI355X achieves 2457.6 GTexel/s, the MI350X achieves 2252.8 GTexel/s. Third, the FP32 and FP16 compute figures: the MI355X delivers 78.64 TFLOPS for both, the MI350X delivers 72.09 TFLOPS for both. Fourth, the power envelope: the MI355X has a TDP of 1400 W and a suggested PSU of 1800 W, while the MI350X has a TDP of 1000 W and a suggested PSU of 1400 W.

All other recorded specifications are identical. The chip is the MI350 256CU for both, the architecture is CDNA 4.0, the process node is 3 nm at TSMC, and the transistor count is 185,000 million on a 2380 mm² die with a density of 77.7M per mm². Memory size, type, bus width, bandwidth, and clock are the same. Shading units, TMUs, ROPs, and pixel rate match. The slot width is OAM Module for both, neither has power connectors, and the bus interface is PCIe 5.0 x16 for both. Display outputs are absent on both, and the dimensions are identical at 102 mm length and 165 mm width. The release date, predecessor, and successor fields are also identical.

Architecture Differences

Both cards share the same CDNA 4.0 architecture, so there are no architectural differences between them. The chip is the MI350 256CU on both, with 16384 shading units and 1024 TMUs. The ROP count is 0 on both, and the pixel rate is 0 MPixel/s, confirming that these are compute accelerators without a rasterization pipeline. Neither card has RT cores or tensor cores listed in the database.

The process node is 3 nm at TSMC for both, with a die size of 2380 mm² and 185,000 million transistors. The transistor density is 77.7M per mm² on both. The memory architecture is identical: 288 GB of HBM3e on an 8192-bit bus with 8.19 TB/s bandwidth and a 2000 MHz clock at 8 Gbps effective.

The API support is identical as well. DirectX, OpenGL, and Vulkan are all listed as N/A for both cards, which aligns with their server-oriented, compute-focused design. The bus interface is PCIe 5.0 x16 for both, and the slot width is OAM Module for both. Neither card has display outputs, and neither has power connectors listed.

The only differences, as noted, are the boost clock, texture rate, FP32/FP16 throughput, and TDP. These are clock and power variations within the same architecture and chip, not fundamental architectural changes. The MI355X runs the same silicon at a higher boost clock, which increases throughput but also increases power draw.

Where Each One Wins

The MI355X wins in raw compute throughput. Its boost clock of 2400 MHz produces 2457.6 GTexel/s, which is 204.8 GTexel/s higher than the MI350X's 2252.8 GTexel/s. In FP32 and FP16 workloads, the MI355X delivers 78.64 TFLOPS, a 6.55 TFLOPS advantage over the MI350X's 72.09 TFLOPS. For compute-bound training or inference tasks where every TFLOPS counts, the MI355X is the stronger choice.

The MI350X wins in power efficiency and system integration. Its TDP of 1000 W is 400 W lower than the MI355X's 1400 W. The suggested PSU of 1400 W is 400 W lower than the MI355X's 1800 W. In dense multi-card deployments where power density and cooling capacity are limiting factors, the MI350X allows more cards per rack or simpler infrastructure. The identical memory subsystem of 288 GB and 8.19 TB/s means the MI350X does not sacrifice memory capacity or bandwidth for its lower power draw.

For workloads that are memory-bound rather than compute-bound, both cards perform identically, since the memory size, bus width, and bandwidth are the same. For workloads that are sensitive to boost clock and texture throughput, the MI355X provides a measurable advantage. The choice between the two depends on whether the 9% compute uplift, derived from the 6.55 TFLOPS difference, is worth the 40% increase in TDP from 1000 W to 1400 W. The database shows no benchmark scores for either card, and both hold the same 50th percentile position, so the win condition for each is defined by the specific deployment constraints: power-limited environments favor the MI350X, performance-maximized environments favor the MI355X.