AMD Instinct MI455X vs NVIDIA N1X 40SM Comparison

Head-to-Head Benchmarks

The database records no head-to-head benchmark results for the AMD Instinct MI455X and the NVIDIA N1X 40SM. Both products have an average benchmark score of zero, and their percentile rankings against all GPUs sit identically at the 50th percentile. The lack of recorded measurements means there are no direct performance comparisons to walk through with exact numbers. What the database does provide are the raw specification deltas, and those differences are substantial.

The AMD Instinct MI455X delivers 157.3 TFLOPS of FP32 compute, while the NVIDIA N1X 40SM delivers 24.02 TFLOPS. That places the MI455X at roughly 6.5 times the FP32 throughput of the N1X 40SM. FP16 performance follows the same ratio, with both parts showing a 1:1 ratio between FP16 and FP32. The MI455X reaches 157.3 TFLOPS in FP16, and the N1X 40SM reaches 24.02 TFLOPS. These are not close figures. The compute gap is the defining feature of this comparison.

Memory bandwidth tells a similar story. The MI455X has 23.3 TB/s of bandwidth, compared to 273.2 GB/s on the N1X 40SM. That is an 85-fold difference in raw memory throughput. The MI455X also has a much larger memory pool at 432 GB versus 128 GB. The bus widths differ enormously as well: 24576 bit on the MI455X versus 256 bit on the N1X 40SM. The memory type separates them too, with HBM4 on the AMD part and LPDDR5X on the NVIDIA part.

Texture rate follows the compute trend. The MI455X reaches 2,457.6 GTexel/s, while the N1X 40SM reaches 750.7 GTexel/s. Pixel rate is a different matter. The MI455X records 0 MPixel/s, which reflects its lack of display outputs and ROP configuration. The N1X 40SM records 93.84 GPixel/s, a figure that aligns with its integrated graphics processor nature and its single HDMI output. For tasks that involve rasterization to a display, the N1X 40SM is the only one of the two that can function at all.

Clock speeds present a mixed picture. The MI455X has a base clock of 1000 MHz and a boost clock of 2400 MHz. The N1X 40SM has a lower base of 741 MHz but a boost of 2346 MHz, which is close to the AMD part. The memory clocks differ: 1900 MHz at 7.6 Gbps effective on the MI455X, versus 1067 MHz at 8.5 Gbps effective on the N1X 40SM. The NVIDIA memory runs at a higher data rate per pin, but the AMD part compensates with an enormously wider bus.

Where Each One Wins

The MI455X wins every compute-heavy category in the database. FP32, FP16, texture rate, memory bandwidth, memory capacity, and bus width all favor the AMD part by wide margins. This is a data center accelerator designed for sustained throughput. The shading unit count of 32768 versus 5120 reinforces that position. The texture mapping unit count of 1024 versus 320 does the same. Any workload that scales with raw arithmetic throughput or memory bandwidth will favor the MI455X.

The N1X 40SM wins in the categories that involve display output and traditional graphics pipeline completion. It has 40 ROPs and a pixel rate of 93.84 GPixel/s. The MI455X has zero ROPs and a pixel rate of 0 MPixel/s. The N1X 40SM also has a single HDMI output, while the MI455X has no outputs at all. For any use case that requires presenting frames on a screen, the N1X 40SM is the only viable option. The NVIDIA part also has 40 RT cores and 160 tensor cores, features that the MI455X does not list in the database. Those specialized units suggest the N1X 40SM carries hardware for ray tracing and tensor operations that the AMD part does not expose in its specifications.

Power behavior splits the two as well. The MI455X has a TDP of 2300 W and a suggested PSU of 2700 W. The N1X 40SM has an unknown TDP and no suggested PSU listed. The AMD part requires an external power infrastructure, while the NVIDIA part, as an IGP, draws from its host platform. The slot widths reflect this: the MI455X is an EAM Module, while the N1X 40SM is an IGP. These are fundamentally different product categories.

Architecture Differences

The MI455X uses the CDNA 5.0 architecture on a 2 nm process from TSMC. The N1X 40SM uses the Blackwell 2.0 architecture on a 5 nm process, also from TSMC. The process node gap is two generations in favor of the AMD part. The MI455X integrates 320,000 million transistors on a die size of 2990 mm², giving a transistor density of 107.0M per mm². The N1X 40SM has a die size of 382 mm² and an unknown transistor count, so density cannot be calculated. The die size difference is roughly 7.8 times in favor of the AMD part.

The chip identifiers also differ. The MI455X uses the MI450 256CU chip, while the N1X 40SM uses the GB20B chip. The generation labels place them in different product families: Instinct (MIx) for AMD and Blackwell IGP (N1x) for NVIDIA. The bus interfaces step apart as well. The MI455X uses PCIe 6.0 x16, while the N1X 40SM uses PCIe 5.0 x16. That is a one-generation gap in interconnect technology.

Memory architecture is a major separator. The MI455X uses HBM4 with a 24576 bit bus and 23.3 TB/s bandwidth. The N1X 40SM uses LPDDR5X with a 256 bit bus and 273.2 GB/s bandwidth. The AMD memory subsystem is built for extreme bandwidth, while the NVIDIA memory subsystem is built for integration efficiency. The MI455X has no display outputs, no ROPs, and no listed RT or tensor cores. The N1X 40SM has display outputs, ROPs, RT cores, and tensor cores. The AMD part is a pure compute accelerator. The NVIDIA part is an integrated GPU with a fuller feature set.

The power connectors are listed as None for both, but the MI455X has a TDP of 2300 W and a suggested PSU of 2700 W. The N1X 40SM has an unknown TDP. The MI455X is an EAM Module, a form factor designed for server integration. The N1X 40SM is an IGP, designed to sit inside a processor package. The production status of the MI455X is not listed, while the N1X 40SM is marked as Active.

FAQ

Q: Which product has higher FP32 compute performance?

A: The AMD Instinct MI455X delivers 157.3 TFLOPS of FP32, compared to 24.02 TFLOPS on the NVIDIA N1X 40SM. The MI455X has roughly 6.5 times the FP32 throughput.

Q: Do both products support FP16 computation?

A: Yes. Both list FP16 at a 1:1 ratio with FP32. The MI455X reaches 157.3 TFLOPS in FP16, and the N1X 40SM reaches 24.02 TFLOPS.

Q: Which product has more memory bandwidth?

A: The MI455X has 23.3 TB/s of bandwidth with a 24576 bit bus and HBM4 memory. The N1X 40SM has 273.2 GB/s with a 256 bit bus and LPDDR5X memory.

Q: Can either product output video?

A: Only the NVIDIA N1X 40SM has display outputs, with 1x HDMI. The AMD Instinct MI455X lists no outputs and a pixel rate of 0 MPixel/s.

Q: What is the process node difference?

A: The MI455X uses a 2 nm process, while the N1X 40SM uses a 5 nm process. Both are manufactured by TSMC.

Q: Which product has RT cores or tensor cores?

A: The N1X 40SM lists 40 RT cores and 160 tensor cores. The MI455X does not list RT cores or tensor cores in the database.

Specification Differences

The two products differ in nearly every recorded specification. The MI455X has 32768 shading units, 1024 TMUs, and 0 ROPs. The N1X 40SM has 5120 shading units, 320 TMUs, and 40 ROPs. The MI455X has 432 GB of HBM4 memory on a 24576 bit bus with 23.3 TB/s bandwidth. The N1X 40SM has 128 GB of LPDDR5X on a 256 bit bus with 273.2 GB/s bandwidth. The MI455X reaches 157.3 TFLOPS in FP32 and FP16. The N1X 40SM reaches 24.02 TFLOPS in both.

Texture rates are 2,457.6 GTexel/s on the MI455X and 750.7 GTexel/s on the N1X 40SM. Pixel rates are 0 MPixel/s and 93.84 GPixel/s respectively. The MI455X has a base clock of 1000 MHz and a boost of 2400 MHz. The N1X 40SM has a base of 741 MHz and a boost of 2346 MHz. Memory clocks are 1900 MHz at 7.6 Gbps effective on the AMD part and 1067 MHz at 8.5 Gbps effective on the NVIDIA part.

The MI455X uses the CDNA 5.0 architecture on a 2 nm TSMC process with 320,000 million transistors on a 2990 mm² die. The N1X 40SM uses Blackwell 2.0 on a 5 nm TSMC process with an unknown transistor count on a 382 mm² die. The MI455X has a TDP of 2300 W and a suggested PSU of 2700 W. The N1X 40SM has an unknown TDP and no suggested PSU. The MI455X is an EAM Module with PCIe 6.0 x16. The N1X 40SM is an IGP with PCIe 5.0 x16. The MI455X has no display outputs. The N1X 40SM has 1x HDMI. The MI455X has no RT cores and no tensor cores listed. The N1X 40SM has 40 RT cores and 160 tensor cores.

The Verdict

The database positions these two parts in entirely separate product categories. The AMD Instinct MI455X is a compute accelerator with 157.3 TFLOPS FP32, 23.3 TB/s memory bandwidth, and 432 GB of HBM4. It has no display outputs, no ROPs, and no listed RT or tensor cores. Its 2300 W TDP and 2700 W suggested PSU indicate a server-grade power envelope. The data supports its use for workloads that demand extreme arithmetic throughput and memory bandwidth.

The NVIDIA N1X 40SM is an integrated GPU with 24.02 TFLOPS FP32, 273.2 GB/s bandwidth, and 128 GB of LPDDR5X. It has 40 ROPs, 40 RT cores, 160 tensor cores, and a single HDMI output. Its pixel rate of 93.84 GPixel/s and display output capability make it functional for graphics presentation. The unknown TDP and IGP form factor point to a part that lives inside a host processor rather than in a dedicated accelerator slot.

Users who need raw compute density should look at the MI455X. The recorded data shows it ahead by approximately 6.5 times in FP32, over 85 times in memory bandwidth, and over 3 times in texture rate. Users who need an integrated part with display output, rasterization, ray tracing, and tensor hardware should look at the N1X 40SM. The two products do not compete in the same segment. The benchmark database shows no direct head-to-head results, which is consistent with the interpretation that these parts serve different purposes. The MI455X is built for computation without display. The N1X 40SM is built for graphics and display within a processor package. The choice between them depends entirely on whether the workload requires display output or maximum compute throughput.