AMD Instinct MI355X vs AMD Radeon RX 6600 LE Comparison

Head-to-Head Benchmarks

The database contains no direct head-to-head benchmark entries for the AMD Instinct MI355X and the AMD Radeon RX 6600 LE. The MI355X has no recorded benchmark scores, an average benchmark score of 0, and a percentile rank of 50 among all GPUs. The RX 6600 LE, by contrast, has two recorded benchmarks: a Geekbench OpenCL score of 69,229 and a Geekbench Vulkan score of 72,428, producing an average benchmark score of 70,829 and a percentile rank of 91.

The absence of recorded scores for the MI355X is not a reflection of capability; it indicates that no standardized benchmark results have been entered into the database for that part. The RX 6600 LE's nearest rivals in the database provide useful context. It sits 1% above the NVIDIA RTX A3000 Mobile (average score 70,140), 1.2% above the NVIDIA Quadro P6000 (average score 69,986), 1.4% above the AMD Radeon Pro WX 8200 (average score 69,870), and 1.3% below the AMD Radeon RX 6650M (average score 71,768). These deltas are small, placing the RX 6600 LE in a tightly contested performance band.

Because the MI355X has no benchmark entries, no quantitative comparison of compute performance can be made from the recorded data. The specification data, however, shows a massive theoretical gulf in raw throughput. The MI355X is rated for 78.64 TFLOPS FP32, while the RX 6600 LE is rated for 8.942 TFLOPS FP32. That is a 8.8x difference in favor of the MI355X. In FP16, the MI355X delivers 78.64 TFLOPS (1:1 ratio), while the RX 6600 LE delivers 17.88 TFLOPS (2:1 ratio). The MI355X also has a texture rate of 2,457.6 GTexel/s versus 279.4 GTexel/s for the RX 6600 LE, an 8.8x gap. The pixel rate comparison is inverted in an unusual way: the MI355X is listed at 0 MPixel/s, while the RX 6600 LE produces 159.7 GPixel/s. The MI355X's 0 MPixel/s reflects its lack of display outputs and traditional raster pipeline rather than a performance measurement.

FAQ

Q: Which GPU has a higher percentile rank among all GPUs in the database?

A: The AMD Radeon RX 6600 LE ranks at the 91st percentile, while the AMD Instinct MI355X ranks at the 50th percentile.

Q: What is the average benchmark score for each GPU?

A: The RX 6600 LE has an average benchmark score of 70,829 across its two recorded tests. The MI355X has an average benchmark score of 0, as no benchmark results are recorded for it.

Q: How does the RX 6600 LE compare to its nearest rivals?

A: It is 1% above the NVIDIA RTX A3000 Mobile, 1.2% above the NVIDIA Quadro P6000, 1.4% above the AMD Radeon Pro WX 8200, and 1.3% below the AMD Radeon RX 6650M.

Q: What memory configurations do the two cards use?

A: The MI355X uses 288 GB of HBM3e memory on a 8192-bit bus with 8.19 TB/s bandwidth. The RX 6600 LE uses 8 GB of GDDR6 memory on a 128-bit bus with 224.0 GB/s bandwidth.

Q: What are the FP32 compute ratings of each card?

A: The MI355X is rated at 78.64 TFLOPS FP32. The RX 6600 LE is rated at 8.942 TFLOPS FP32.

Q: What display outputs does each card provide?

A: The MI355X has no display outputs. The RX 6600 LE provides 1x HDMI 2.1 and 3x DisplayPort 1.4a.

Architecture Differences

The two GPUs target fundamentally different workloads, and the architecture data confirms this. The MI355X uses CDNA 4.0 architecture, built on a 3 nm process at TSMC with 185,000 million transistors on a 2380 mm² die, yielding a transistor density of 77.7M per mm². The RX 6600 LE uses RDNA 2.0 architecture, built on a 7 nm process at TSMC with 11,060 million transistors on a 237 mm² die, yielding a transistor density of 46.7M per mm². The MI355X is a massive compute accelerator; the RX 6600 LE is a compact consumer graphics card.

The MI355X uses the MI350 256CU chip, which indicates 256 compute units. The RX 6600 LE uses the Navi 23 chip. The MI355X has 16,384 shading units, 1,024 texture mapping units, and 0 ROPs. The RX 6600 LE has 1,792 shading units, 112 texture mapping units, and 64 ROPs, plus 28 ray tracing cores. The MI355X has no listed ray tracing cores. The MI355X's pixel rate is listed as 0 MPixel/s, consistent with its lack of a traditional raster output stage and no display outputs.

Memory architecture differs sharply. The MI355X uses HBM3e with 288 GB capacity, an 8192-bit bus, and 8.19 TB/s bandwidth. The RX 6600 LE uses GDDR6 with 8 GB capacity, a 128-bit bus, and 224.0 GB/s bandwidth. The MI355X's memory bandwidth is 36.6x higher. The MI355X supports a 1:1 FP16/FP32 ratio, meaning it does not double FP16 throughput, while the RX 6600 LE uses a 2:1 ratio, doubling FP16 throughput relative to FP32. The MI355X exposes no API support for DirectX, OpenGL, or Vulkan, which is typical for a compute-focused accelerator. The RX 6600 LE supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4.

The physical and power profiles are also divergent. The MI355X is an OAM module, 102 mm long and 165 mm wide, with a 1400 W TDP and a suggested PSU of 1800 W. It has no power connectors because OAM modules receive power through the socket. The RX 6600 LE is a dual-slot card, 190 mm long, 110 mm high, and 40 mm wide, with a 132 W TDP, a single 8-pin power connector, and a suggested PSU of 300 W. The MI355X uses PCIe 5.0 x16; the RX 6600 LE uses PCIe 4.0 x8.

Specification Differences

The two parts differ in nearly every measurable specification. The MI355X uses a 3 nm process; the RX 6600 LE uses 7 nm. Transistor count is 185,000 million versus 11,060 million. Die size is 2380 mm² versus 237 mm². Transistor density is 77.7M per mm² versus 46.7M per mm². Base clock is 1000 MHz for the MI355X versus 1626 MHz for the RX 6600 LE. Boost clock is 2400 MHz versus 2495 MHz. The RX 6600 LE also lists a game clock of 2045 MHz; the MI355X has no game clock. Memory clock is 2000 MHz (8 Gbps effective) for the MI355X versus 1750 MHz (14 Gbps effective) for the RX 6600 LE.

Memory size is 288 GB versus 8 GB. Memory type is HBM3e versus GDDR6. Bus width is 8192 bit versus 128 bit. Bandwidth is 8.19 TB/s versus 224.0 GB/s. Shading units are 16,384 versus 1,792. TMUs are 1,024 versus 112. ROPs are 0 versus 64. The RX 6600 LE has 28 ray tracing cores; the MI355X lists none. Pixel rate is 0 MPixel/s versus 159.7 GPixel/s. Texture rate is 2,457.6 GTexel/s versus 279.4 GTexel/s. FP32 is 78.64 TFLOPS versus 8.942 TFLOPS. FP16 is 78.64 TFLOPS (1:1) versus 17.88 TFLOPS (2:1). TDP is 1400 W versus 132 W. Slot width is OAM Module versus dual-slot. Power connectors are none versus 1x 8-pin. Suggested PSU is 1800 W versus 300 W. Bus interface is PCIe 5.0 x16 versus PCIe 4.0 x8. Display outputs are none versus 1x HDMI 2.1 and 3x DisplayPort 1.4a.

API support differs completely. The MI355X lists N/A for DirectX, OpenGL, and Vulkan. The RX 6600 LE lists DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. Dimensions differ: the MI355X is 102 mm long and 165 mm wide with no listed height; the RX 6600 LE is 190 mm long, 110 mm high, and 40 mm wide. Release dates differ: the MI355X released on 2025-06-11, the RX 6600 LE on 2023-12-07. The RX 6600 LE has an active production status; the MI355X has none listed. The MI355X's predecessor is Radeon Instinct, while the RX 6600 LE's predecessor is Navi and its successor is Navi III.

The Verdict

The recorded data supports a clear separation of roles. The AMD Instinct MI355X is a compute accelerator with no display outputs, no consumer API support, an OAM form factor, and a 1400 W TDP. It delivers 78.64 TFLOPS FP32, 288 GB of HBM3e memory, and 8.19 TB/s of memory bandwidth. Its 50th percentile rank is based on zero recorded benchmarks, so its standing in the database reflects missing data rather than measured performance. The AMD Radeon RX 6600 LE is a consumer graphics card with display outputs, full DirectX 12 Ultimate support, a dual-slot form factor, and a 132 W TDP. It delivers 8.942 TFLOPS FP32, 8 GB of GDDR6 memory, and 224.0 GB/s of memory bandwidth, and its 91st percentile rank is based on two recorded benchmarks.

The MI355X is not a replacement for the RX 6600 LE in a desktop build. It has no video outputs, no graphics API support, and cannot render to a display. The RX 6600 LE, conversely, is not a substitute for the MI355X in a compute environment: its FP32 throughput is 8.79x lower, its memory bandwidth is 36.6x lower, and its memory capacity is 36x smaller. The MI355X's 3 nm process and 185,000 million transistors make it a fundamentally different class of silicon. The RX 6600 LE's 7 nm process and 11,060 million transistors place it in the mainstream consumer segment. The data shows two products designed for different markets, with no overlap in form factor, power delivery, memory subsystem, or intended use.

Where Each One Wins

The MI355X wins in raw compute throughput. Its 78.64 TFLOPS FP32 rating is 8.8x higher than the RX 6600 LE's 8.942 TFLOPS. Its texture rate of 2,457.6 GTexel/s is 8.8x higher. Its FP16 output is 78.64 TFLOPS at a 1:1 ratio, which is 4.4x higher than the RX 6600 LE's 17.88 TFLOPS at a 2:1 ratio. Its memory subsystem is vastly larger: 288 GB versus 8 GB, 8.19 TB/s versus 224.0 GB/s, and an 8192-bit bus versus a 128-bit bus. The MI355X also uses a more advanced 3 nm process with higher transistor density (77.7M per mm² versus 46.7M per mm²) and a newer PCIe interface (5.0 x16 versus 4.0 x8). It released later, on 2025-06-11.

The RX 6600 LE wins in every metric relevant to a desktop graphics card. It has 64 ROPs versus 0, a pixel rate of 159.7 GPixel/s versus 0 MPixel/s, and 28 ray tracing cores versus none. It supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, while the MI355X lists N/A for all three. It provides 1x HDMI 2.1 and 3x DisplayPort 1.4a outputs, while the MI355X has none. It has a much lower TDP of 132 W versus 1400 W, a lower suggested PSU of 300 W versus 1800 W, and uses a standard 8-pin power connector instead of relying on OAM socket power. It is a dual-slot card with a compact 190 mm length, while the MI355X is an OAM module. The RX 6600 LE also has recorded benchmark results, ranking at the 91st percentile, and it is the only one of the two with nearest rivals in the database, all within 1.4% of its average score. The RX 6600 LE released earlier on 2023-12-07 and has an active production status. For any workload involving rendering, ray tracing, display output, or standard graphics APIs, the RX 6600 LE is the functional choice. For massive parallel compute with enormous memory capacity and bandwidth, the MI355X is the designated part.