AMD Radeon 840M vs AMD Radeon RX 7900M Comparison

Head-to-Head Benchmarks

The recorded data shows a clear performance hierarchy between these two AMD mobile graphics solutions. The AMD Radeon RX 7900M sits in the 94th percentile of all GPUs in the database, while the AMD Radeon 840M registers at the 50th percentile. This gap reflects a fundamental difference in their design targets.

The RX 7900M delivers an average benchmark score of 97,487 across its recorded tests. Its nearest rival in the database, the AMD Radeon Pro VII, posts an average score of 97,131, placing the RX 7900M just 0.4% ahead. The NVIDIA Quadro RTX 6000 scores 101,872, which puts it 4.3% ahead of the RX 7900M. Against the AMD Radeon Instinct MI60, which scores 92,466, the RX 7900M leads by 5.4%. The NVIDIA RTX A4500 trails further behind at 91,671, a 6.3% deficit to the RX 7900M.

The 840M has no recorded benchmark scores or nearest rivals in the database. Its average benchmark score is listed as zero, and its percentile ranking of 50 places it at the midpoint of all GPUs tracked. This makes direct numeric comparison impossible, but the architectural and specification differences explain the performance chasm.

In raw compute throughput, the RX 7900M delivers 38.52 TFLOPS of FP32 performance. The 840M produces 1,484.8 GFLOPS, which equals roughly 1.48 TFLOPS. The RX 7900M therefore provides approximately 26 times the FP32 throughput. This is the single largest arithmetic gap in the dataset.

Pixel processing shows a similar story. The RX 7900M achieves a pixel rate of 401.3 GPixel/s, while the 840M manages 23.20 GPixel/s. Texture rate favors the larger chip as well: 601.9 GTexel/s for the RX 7900M versus 46.40 GTexel/s for the 840M.

The RX 7900M also leads in ray tracing resources with 72 RT cores compared to 4 RT cores on the 840M. Shading unit count differs by a factor of 18, with 4,608 on the RX 7900M and 256 on the 840M. TMUs stand at 288 versus 16, and ROPs at 192 versus 8.

Clock speeds present an interesting inversion. The 840M has a boost clock of 2900 MHz, which is higher than the RX 7900M's boost of 2090 MHz. The base clocks differ in the opposite direction: 400 MHz for the 840M and 1825 MHz for the RX 7900M. The 840M's high boost and low base suggest a bursty, power-limited design, while the RX 7900M maintains a higher floor.

Memory bandwidth favors the RX 7900M decisively. It uses 16 GB of GDDR6 memory on a 256-bit bus, delivering 576.0 GB/s of bandwidth. The 840M relies on system-shared memory with bandwidth described as system dependent. The RX 7900M's memory operates at 2250 MHz with 18 Gbps effective transfer.

Where Each One Wins

The RX 7900M wins in every category where the database records measurable performance. Its strength lies in sustained, high-throughput workloads. The 38.52 TFLOPS FP32 figure, 601.9 GTexel/s texture rate, and 401.3 GPixel/s pixel rate position it for demanding rendering tasks. The 72 RT cores give it substantial ray tracing capability. The 16 GB GDDR6 frame buffer with 576.0 GB/s bandwidth supports large textures and high-resolution rendering without spilling to system memory.

The 840M wins in power efficiency and integration. Its 15 W TDP contrasts sharply with the RX 7900M's 180 W TDP. The 840M uses system-shared memory, eliminating dedicated VRAM and its associated power draw. It requires no power connectors, matching the RX 7900M in that respect, but its bus interface of PCIe 4.0 x8 halves the lane count of the RX 7900M's PCIe 4.0 x16 connection.

The 840M's boost clock of 2900 MHz exceeds the RX 7900M's 2090 MHz boost. In short, lightly threaded workloads that scale with clock speed rather than core count, the 840M's higher boost could provide a relative advantage. However, the database contains no benchmarks for the 840M to confirm this behavior.

Thermal design separates the two clearly. The 840M's 15 W envelope suits thin-and-light portable devices. The RX 7900M's 180 W envelope requires substantial cooling and power delivery, limiting it to larger laptops. The 840M uses the Krackan Point chip with RDNA 3.5 architecture, while the RX 7900M uses Navi 31 with RDNA 3.0.

Both GPUs support DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. API feature parity means software compatibility is not a differentiator. The production status for both is listed as active.

FAQ

Q: Which GPU has the higher benchmark score?

A: The AMD Radeon RX 7900M has an average benchmark score of 97,487 and sits in the 94th percentile. The AMD Radeon 840M has no recorded benchmark scores and sits in the 50th percentile.

Q: How does the RX 7900M compare to its nearest rivals?

A: The RX 7900M is 0.4% ahead of the AMD Radeon Pro VII, 5.4% ahead of the AMD Radeon Instinct MI60, and 6.3% ahead of the NVIDIA RTX A4500. The NVIDIA Quadro RTX 6000 leads it by 4.3%.

Q: What is the FP32 performance difference?

A: The RX 7900M delivers 38.52 TFLOPS of FP32 performance. The 840M delivers 1,484.8 GFLOPS, approximately 1.48 TFLOPS. The RX 7900M has roughly 26 times the FP32 throughput.

Q: Do both GPUs support the same APIs?

A: Yes. Both support DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4.

Q: What memory configurations do they use?

A: The RX 7900M uses 16 GB of GDDR6 memory on a 256-bit bus with 576.0 GB/s bandwidth. The 840M uses system-shared memory with system-dependent bandwidth.

Q: What are the TDP figures for each?

A: The 840M has a TDP of 15 W. The RX 7900M has a TDP of 180 W.

Specification Differences

The RX 7900M uses the Navi 31 chip with RDNA 3.0 architecture and a codename of Plum Bonito. The 840M uses the Krackan Point chip with RDNA 3.5 architecture. The process nodes differ: 5 nm for the RX 7900M, 4 nm for the 840M. Both use TSMC as the foundry.

The RX 7900M has 57,700 million transistors on a 529 mm² die, with a transistor density of 109.1M per mm². The 840M's transistor count and die size are listed as unknown.

Clock specifications diverge. The 840M has a base clock of 400 MHz and boost of 2900 MHz. The RX 7900M has a base of 1825 MHz and boost of 2090 MHz. Memory clocks differ as well: the RX 7900M runs at 2250 MHz with 18 Gbps effective, while the 840M uses system shared memory.

Core configuration differences are substantial. The 840M has 256 shading units, 16 TMUs, 8 ROPs, and 4 RT cores. The RX 7900M has 4,608 shading units, 288 TMUs, 192 ROPs, and 72 RT cores.

Memory capacity and type differ completely. The RX 7900M has 16 GB of GDDR6 on a 256-bit bus with 576.0 GB/s bandwidth. The 840M has system shared memory with a system shared bus width and system dependent bandwidth.

Power requirements separate the pair. The 840M draws 15 W, the RX 7900M draws 180 W. Neither uses power connectors, and both are listed with an IGP slot width.

The bus interface differs: PCIe 4.0 x8 for the 840M, PCIe 4.0 x16 for the RX 7900M. Both use portable device dependent display outputs.

Release dates sit roughly 16 months apart. The RX 7900M launched on 2023-10-18, the 840M on 2025-02-28. The RX 7900M belongs to the Radeon RX 7000 series and the Navi Mobile (RX 7000M) generation. The 840M belongs to the Navi III IGP (Strix Point Mobile) generation.

FP16 performance differs in ratio. The 840M achieves 1,484.8 GFLOPS with a 1:1 FP16 to FP32 ratio. The RX 7900M achieves 77.05 TFLOPS with a 2:1 ratio.

Architecture Differences

The 840M uses RDNA 3.5, a newer architecture iteration than the RX 7900M's RDNA 3.0. The 840M's chip, Krackan Point, is built on a 4 nm TSMC process. The RX 7900M's Navi 31 chip uses a 5 nm TSMC process. The smaller node gives the 840M a density advantage per unit area, though its die size remains unknown.

The RX 7900M's Navi 31 is a large discrete-class GPU with 57,700 million transistors spread across 529 mm². This makes it a high-complexity design intended for maximum throughput. The 840M's Krackan Point is an integrated graphics processor, as indicated by its IGP slot width and system-shared memory.

Core architecture scales with the chip size. The RX 7900M's 4,608 shading units and 72 RT cores represent a full-scale RDNA 3.0 implementation. The 840M's 256 shading units and 4 RT cores represent a minimal configuration of RDNA 3.5. The 840M compensates with a 2900 MHz boost clock, the highest in this comparison.

Memory architecture reflects their different roles. The RX 7900M uses dedicated GDDR6 with a 256-bit interface and 576.0 GB/s bandwidth. The 840M shares system memory, making its bandwidth dependent on the host platform. This is a structural difference, not a tuning difference.

The RX 7900M's FP16 throughput of 77.05 TFLOPS at a 2:1 ratio indicates hardware optimized for mixed-precision workloads. The 840M's 1:1 FP16 ratio at 1,484.8 GFLOPS means no throughput advantage for half-precision work.

Both architectures support the same API set, including DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. Neither has tensor cores listed in the database.

Clock behavior highlights their different power philosophies. The 840M's 400 MHz base to 2900 MHz boost spread allows aggressive power gating. The RX 7900M's 1825 MHz base to 2090 MHz boost spread reflects a design that stays near its operating ceiling.

The RX 7900M's predecessor is listed as Polaris Mobile. The 840M's predecessor is Navi II IGP. Neither has a successor listed. Both remain in active production.

The generation labels place them in different product families. The RX 7900M is part of the Navi Mobile (RX 7000M) generation within the Radeon RX 7000 series. The 840M is part of the Navi III IGP (Strix Point Mobile) generation with no series designation.