AMD Radeon R5 M420 vs NVIDIA GeForce GT 645M Comparison

The Verdict

The data presents a clear but narrow split between these two mobile graphics parts. The NVIDIA GeForce GT 645M and AMD Radeon R5 M420 are closely matched in overall standing, with the NVIDIA part sitting at the 26th percentile of all GPUs and the AMD part at the 23rd percentile. The single recorded head-to-head benchmark, Geekbench OpenCL, favors the AMD Radeon R5 M420 by a substantial margin, with a score of 3956 against 2680 for the NVIDIA GeForce GT 645M, a difference of 32.3% in AMD's favor.

Looking at the broader benchmark averages, the NVIDIA GeForce GT 645M posts an average score of 4411 across three tests, while the AMD Radeon R5 M420 has an average of 3956 from a single test. The NVIDIA part demonstrates more consistent capability across different compute APIs, with its Geekbench Metal score of 5679 and Vulkan score of 4875 showing strength beyond the OpenCL workload. The AMD part has no recorded Metal or Vulkan scores in the database, which limits its measured versatility.

For users prioritizing OpenCL compute performance, the AMD Radeon R5 M420 is the better choice based on the direct comparison. For users who need broader API support and higher peak scores in Metal and Vulkan workloads, the NVIDIA GeForce GT 645M offers advantages that the AMD part cannot match in the recorded data. The AMD part does carry twice the memory capacity at 4 GB versus 2 GB, which may matter for certain workloads, but the memory bus width is half that of the NVIDIA part, and the bandwidth is considerably lower at 16.00 GB/s versus 28.80 GB/s.

The NVIDIA GeForce GT 645M also edges out its direct rivals in the database. It sits 0.5% ahead of the NVIDIA GeForce 930M, 1.2% ahead of the Intel Iris Pro Graphics 5200, and 1.8% ahead of the NVIDIA GeForce RTX 4070 GDDR6 in average score, while trailing the AMD Radeon R7 M260 by 1.9%. The AMD Radeon R5 M420, by contrast, is essentially tied with the NVIDIA GeForce 830M at 0% delta, sits 0.1% ahead of the NVIDIA GeForce GT 745M, but trails the NVIDIA Quadro K2000 by 0.2% and the AMD Radeon HD 6850 X2 by 0.5%. Neither card is a performance leader in its respective peer group; both are firmly in the lower quartile of the database.

Architecture Differences

The two GPUs come from different architectural families and different generations. The NVIDIA GeForce GT 645M is built on the GK107 chip using the Kepler architecture, part of the GeForce 600M generation. The AMD Radeon R5 M420 uses the Jet chip with GCN 1.0 architecture, belonging to the Gem System (R5 M400) generation. Both are fabricated by TSMC on a 28 nm process, so the manufacturing node is identical.

The transistor counts differ notably. The NVIDIA chip contains 1,270 million transistors on a 118 mm² die, resulting in a transistor density of 10.8M per mm². The AMD chip packs 690 million transistors onto a 56 mm² die, achieving a higher density of 12.3M per mm². The AMD chip is smaller in both absolute transistor count and die area, but it packs those transistors more tightly.

The compute resources are organized differently. The NVIDIA GeForce GT 645M has 384 shading units, 32 texture mapping units, and 16 render output units. The AMD Radeon R5 M420 has 320 shading units, 20 TMUs, and only 8 ROPs. Despite having fewer shading units, the AMD part runs at higher clock speeds, with a base clock of 780 MHz and a boost clock of 850 MHz, compared to the NVIDIA base of 709 MHz and boost of 780 MHz.

Neither GPU includes dedicated ray tracing cores or tensor cores, which aligns with their older architectural designs. The feature sets are otherwise differentiated by API support levels. The NVIDIA part supports DirectX 12 (11_0), while the AMD part supports DirectX 12 (11_1), a slightly higher feature level. Both support OpenGL 4.6. Vulkan support is nearly identical, with the NVIDIA part at version 1.2.175 and the AMD part at 1.2.170.

The memory subsystems take fundamentally different approaches. The NVIDIA GeForce GT 645M uses 2 GB of DDR3 on a 128-bit bus, delivering 28.80 GB/s of bandwidth. The AMD Radeon R5 M420 uses 4 GB of DDR3 on a 64-bit bus, delivering only 16.00 GB/s. The AMD part has double the capacity but less than 60% of the bandwidth. The memory clocks are 900 MHz (1800 Mbps effective) for the NVIDIA part and 1000 MHz (2 Gbps effective) for the AMD part, so the AMD memory runs faster per pin but the narrow bus limits total throughput.

The bus interface also differs. The NVIDIA part uses PCIe 3.0 x16, while the AMD part uses PCIe 3.0 x8. Both are integrated into portable devices, with display outputs described as "Portable Device Dependent" and both using an IGP slot width.

Head-to-Head Benchmarks

The database contains exactly one direct head-to-head benchmark between these two parts: Geekbench OpenCL. The AMD Radeon R5 M420 scores 3956, while the NVIDIA GeForce GT 645M scores 2680. This is a 32.3% advantage for the AMD part, a decisive margin in a compute workload. The AMD part achieves this despite having fewer shading units, 320 versus 384, and lower peak FP32 throughput. The recorded FP32 for the AMD part is 544.0 GFLOPS, while the NVIDIA part reaches 599.0 GFLOPS. The AMD advantage in this test likely stems from its higher clock speeds and architectural efficiency in OpenCL dispatch.

The NVIDIA GeForce GT 645M, however, shows strength in other benchmark categories that the AMD part has not recorded. The NVIDIA part scores 5679 in Geekbench Metal and 4875 in Geekbench Vulkan. These scores are significantly higher than its own OpenCL result, suggesting that the Kepler architecture handles these APIs more effectively. The AMD Radeon R5 M420 has no Metal or Vulkan scores in the database, so no direct comparison is possible for those workloads.

Looking at the average benchmark scores, the NVIDIA GeForce GT 645M averages 4411 across its three recorded tests, which places it 11.5% above the AMD part's single-test average of 3956. This aggregate figure tells a different story than the head-to-head OpenCL result. The NVIDIA part is more consistent across API types, while the AMD part excels specifically in OpenCL.

In the context of their nearest rivals, the NVIDIA GeForce GT 645M's average of 4411 puts it ahead of the NVIDIA GeForce 930M (4388, +0.5%), the Intel Iris Pro Graphics 5200 (4360, +1.2%), and the NVIDIA GeForce RTX 4070 GDDR6 (4335, +1.8%), while trailing the AMD Radeon R7 M260 (4499, -1.9%). The AMD Radeon R5 M420's average of 3956 is statistically tied with the NVIDIA GeForce 830M (3957, 0%) and the NVIDIA GeForce GT 745M (3953, +0.1%), while slightly trailing the NVIDIA Quadro K2000 (3964, -0.2%) and the AMD Radeon HD 6850 X2 (3977, -0.5%). These rival comparisons are tightly clustered, indicating that both cards sit at the same performance tier relative to their peers.

Specification Differences

The following fields differ between the two parts in the recorded data:

• Chip: GK107 (NVIDIA) versus Jet (AMD)
• Architecture: Kepler (NVIDIA) versus GCN 1.0 (AMD)
• Generation: GeForce 600M (NVIDIA) versus Gem System (R5 M400) (AMD)
• Transistors: 1,270 million (NVIDIA) versus 690 million (AMD)
• Die size: 118 mm² (NVIDIA) versus 56 mm² (AMD)
• Transistor density: 10.8M / mm² (NVIDIA) versus 12.3M / mm² (AMD)
• Base clock: 709 MHz (NVIDIA) versus 780 MHz (AMD)
• Boost clock: 780 MHz (NVIDIA) versus 850 MHz (AMD)
• Memory clock: 900 MHz, 1800 Mbps effective (NVIDIA) versus 1000 MHz, 2 Gbps effective (AMD)
• Memory size: 2 GB (NVIDIA) versus 4 GB (AMD)
• Memory bus width: 128 bit (NVIDIA) versus 64 bit (AMD)
• Memory bandwidth: 28.80 GB/s (NVIDIA) versus 16.00 GB/s (AMD)
• Shading units: 384 (NVIDIA) versus 320 (AMD)
• TMUs: 32 (NVIDIA) versus 20 (AMD)
• ROPs: 16 (NVIDIA) versus 8 (AMD)
• Pixel rate: 6.240 GPixel/s (NVIDIA) versus 6.800 GPixel/s (AMD)
• Texture rate: 24.96 GTexel/s (NVIDIA) versus 17.00 GTexel/s (AMD)
• FP32: 599.0 GFLOPS (NVIDIA) versus 544.0 GFLOPS (AMD)
• TDP: 32 W (NVIDIA) versus not recorded (AMD)
• Power connectors: None (NVIDIA) versus not recorded (AMD)
• Bus interface: PCIe 3.0 x16 (NVIDIA) versus PCIe 3.0 x8 (AMD)
• DirectX support: 12 (11_0) (NVIDIA) versus 12 (11_1) (AMD)
• Vulkan support: 1.2.175 (NVIDIA) versus 1.2.170 (AMD)
• Release date: 2012-09-30 (NVIDIA) versus 2016-05-14 (AMD)
• Predecessor: GeForce 500M (NVIDIA) versus Solar System (AMD)
• Successor: GeForce 700M (NVIDIA) versus Polaris Mobile (AMD)
• Benchmark scores: Geekbench Metal 5679 and Geekbench Vulkan 4875 present for NVIDIA, absent for AMD
• Average benchmark score: 4411 (NVIDIA) versus 3956 (AMD)
• Percentile: 26 (NVIDIA) versus 23 (AMD)

Fields that are identical include the process node (28 nm), foundry (TSMC), memory type (DDR3), slot width (IGP), display outputs (Portable Device Dependent), OpenGL support (4.6), and production status (End-of-life). Neither part has a recorded launch MSRP.

FAQ

Q: Which GPU has the higher average benchmark score?

A: The NVIDIA GeForce GT 645M has an average benchmark score of 4411 across three tests, while the AMD Radeon R5 M420 averages 3956 from a single test.

Q: How much faster is the AMD Radeon R5 M420 in the head-to-head OpenCL test?

A: The AMD part scores 3956 in Geekbench OpenCL versus 2680 for the NVIDIA part, a 32.3% advantage.

Q: Does the NVIDIA GeForce GT 645M support Metal or Vulkan?

A: Yes, the database records Geekbench Metal at 5679 and Geekbench Vulkan at 4875 for the NVIDIA part. No Metal or Vulkan scores are recorded for the AMD Radeon R5 M420.

Q: Which GPU has more memory bandwidth?

A: The NVIDIA GeForce GT 645M, with 28.80 GB/s on a 128-bit bus. The AMD Radeon R5 M420 has 16.00 GB/s on a 64-bit bus, despite having 4 GB of memory versus 2 GB.

Q: How do these cards compare to their nearest rivals?

A: The NVIDIA part is 0.5% ahead of the GeForce 930M and 1.8% ahead of the GeForce RTX 4070 GDDR6, but 1.9% behind the Radeon R7 M260. The AMD part is tied with the GeForce 830M at 0% and trails the Quadro K2000 by 0.2%.

Q: Which card has the higher pixel fill rate?

A: The AMD Radeon R5 M420 has a pixel rate of 6.800 GPixel/s, slightly higher than the NVIDIA GeForce GT 645M's 6.240 GPixel/s, even though the NVIDIA part has 16 ROPs versus 8.

Q: What are the transistor counts and die sizes?

A: The NVIDIA GK107 chip has 1,270 million transistors on a 118 mm² die. The AMD Jet chip has 690 million transistors on a 56 mm² die. The AMD chip has a higher transistor density at 12.3M per mm² versus 10.8M per mm².