AMD Radeon R5 M420 vs NVIDIA GeForce GT 755M Comparison

The Verdict

The benchmark data separates these two mobile GPUs clearly. The NVIDIA GeForce GT 755M wins the only head-to-head test, the Geekbench OpenCL benchmark, with a score of 4934 against the AMD Radeon R5 M420's 3956. That is a 24.7% advantage for the NVIDIA part. The GT 755M also holds a higher average benchmark score of 4033 versus 3956 for the AMD part. Looking at percentile rankings, the GT 755M sits at the 24th percentile of all GPUs, and the R5 M420 sits just below at the 23rd percentile.

Given the data, the choice is straightforward: the NVIDIA GeForce GT 755M is the stronger performer in every measured category. Its higher raw compute throughput, faster memory subsystem, and superior benchmark results make it the pick for anyone prioritizing graphics performance in a laptop. The AMD Radeon R5 M420, despite having double the memory capacity (4 GB versus 2 GB), cannot overcome its slower DDR3 memory and lower clock speeds. The data indicates the R5 M420 is best suited for basic display output and light, non-demanding tasks where its larger frame buffer might be a secondary consideration. For gaming, content creation, or any GPU-accelerated workload, the GT 755M is the definitive choice based on the numbers.

Architecture Differences

The two GPUs come from different architectural generations and design philosophies. The NVIDIA GeForce GT 755M is built on the Kepler architecture, using the GK107 chip. The AMD Radeon R5 M420 uses the GCN 1.0 architecture with the Jet chip. Both are fabricated by TSMC on a 28 nm process node, but the similarities end there.

The transistor counts differ substantially. The NVIDIA chip contains 1,270 million transistors on a die size of 118 mm², giving it a transistor density of 10.8 million transistors per square millimeter. The AMD chip is much smaller, with 690 million transistors on a 56 mm² die, resulting in a higher density of 12.3 million transistors per square millimeter. This means the AMD chip packs its transistors more tightly, but the NVIDIA chip has nearly double the total transistor budget to work with.

The shading resources also differ. The GT 755M has 384 shading units, 32 texture mapping units (TMUs), and 16 raster operation units (ROPs). The R5 M420 has 320 shading units, 20 TMUs, and only 8 ROPs. This gives the NVIDIA part 64 more shading units, 12 more TMUs, and double the ROP count. The additional ROPs are particularly significant for pixel fill rate and overall rendering efficiency.

Memory architecture is another major divergence. The GT 755M uses 2 GB of GDDR5 memory on a 128-bit bus, while the R5 M420 uses 4 GB of DDR3 memory on a 64-bit bus. The memory clock speeds reflect this difference: the NVIDIA part runs at 1350 MHz with 5.4 Gbps effective data rate, while the AMD part runs at 1000 MHz with 2 Gbps effective. This leads to a massive bandwidth disparity: 86.40 GB/s for the GT 755M versus 16.00 GB/s for the R5 M420. The GDDR5 memory on the NVIDIA part is fundamentally faster than the DDR3 on the AMD part.

Clock speeds tell a similar story. The GT 755M has a base clock of 980 MHz and a boost clock of 1020 MHz. The R5 M420 has a base clock of 780 MHz and a boost clock of 850 MHz. The NVIDIA part runs at higher frequencies across the board. Also, the bus interface differs: the GT 755M uses PCIe 3.0 x16, while the R5 M420 uses PCIe 3.0 x8, halving the potential bandwidth to the host system.

Head-to-Head Benchmarks

The only direct head-to-head benchmark in the data is the Geekbench OpenCL test. The NVIDIA GeForce GT 755M scores 4934 against the AMD Radeon R5 M420's 3956. This represents a 24.7% delta in favor of the NVIDIA part. This is a substantial margin, indicating a significant performance gap in general-purpose GPU compute workloads.

Breaking down the theoretical numbers explains why the gap is so large. The GT 755M's FP32 performance is 783.4 GFLOPS, compared to 544.0 GFLOPS for the R5 M420. That is a 44% advantage in raw floating-point throughput. The pixel rate is 8.160 GPixel/s for the NVIDIA part versus 6.800 GPixel/s for the AMD part. The texture rate is 32.64 GTexel/s versus 17.00 GTexel/s, a 92% advantage for the NVIDIA part. Each of these figures contributes to the overall OpenCL score.

The memory bandwidth difference is the most stark. At 86.40 GB/s, the GT 755M has 5.4 times the bandwidth of the R5 M420's 16.00 GB/s. In memory-bound workloads, this is a decisive factor. The NVIDIA part's wider 128-bit bus and faster GDDR5 memory simply outclass the AMD part's 64-bit bus and DDR3 memory. Even though the R5 M420 has more memory capacity, that capacity is useless without the bandwidth to feed it efficiently.

The R5 M420 does not win any head-to-head benchmarks in the data. The wins column shows 1 for the NVIDIA part and 0 for the AMD part. The data offers no category where the AMD GPU comes out ahead.

Specification Differences

The following specifications differ between the two GPUs:

• Chip: NVIDIA GK107 versus AMD Jet
• Architecture: Kepler versus GCN 1.0
• Generation: GeForce 700M versus Gem System (R5 M400)
• Transistor Count: 1,270 million versus 690 million
• Die Size: 118 mm² versus 56 mm²
• Transistor Density: 10.8M / mm² versus 12.3M / mm²
• Base Clock: 980 MHz versus 780 MHz
• Boost Clock: 1020 MHz versus 850 MHz
• Memory Size: 2 GB versus 4 GB
• Memory Type: GDDR5 versus DDR3
• Memory Bus Width: 128 bit versus 64 bit
• Memory Bandwidth: 86.40 GB/s versus 16.00 GB/s
• Memory Clock: 1350 MHz (5.4 Gbps effective) versus 1000 MHz (2 Gbps effective)
• Shading Units: 384 versus 320
• TMUs: 32 versus 20
• ROPs: 16 versus 8
• Pixel Rate: 8.160 GPixel/s versus 6.800 GPixel/s
• Texture Rate: 32.64 GTexel/s versus 17.00 GTexel/s
• FP32 Performance: 783.4 GFLOPS versus 544.0 GFLOPS
• TDP: 50 W versus not specified
• Slot Width: MXM Module versus IGP
• Power Connectors: None versus not specified
• Bus Interface: PCIe 3.0 x16 versus PCIe 3.0 x8
• DirectX Support: 12 (11_0) versus 12 (11_1)
• Vulkan Support: 1.2.175 versus 1.2.170
• Release Date: 2013-06-24 versus 2016-05-14
• Predecessor: GeForce 600M versus Solar System
• Successor: GeForce 800M versus Polaris Mobile
• Geekbench OpenCL Score: 4934 versus 3956
• Average Benchmark Score: 4033 versus 3956
• Percentile vs All GPUs: 24 versus 23

The GT 755M was released earlier but offers superior specifications in nearly every performance-relevant category. The R5 M420 was released later but with a smaller, less capable chip.

FAQ

Q: Which GPU has a higher average benchmark score?

A: The NVIDIA GeForce GT 755M has an average benchmark score of 4033, while the AMD Radeon R5 M420 has an average score of 3956. The NVIDIA part leads by 77 points.

Q: How much faster is the GT 755M in the Geekbench OpenCL test?

A: The GT 755M scores 4934 compared to the R5 M420's 3956, giving the NVIDIA part a 24.7% advantage in that specific benchmark.

Q: Does the AMD Radeon R5 M420 have more memory than the NVIDIA part?

A: Yes, the R5 M420 has 4 GB of DDR3 memory, while the GT 755M has 2 GB of GDDR5 memory. However, the GT 755M has much higher memory bandwidth at 86.40 GB/s versus 16.00 GB/s.

Q: What is the percentile ranking of each GPU?

A: The NVIDIA GeForce GT 755M is at the 24th percentile of all GPUs, while the AMD Radeon R5 M420 is at the 23rd percentile. Both are near the bottom of the performance spectrum.

Q: Which GPU has a higher pixel fill rate?

A: The NVIDIA GeForce GT 755M has a pixel rate of 8.160 GPixel/s, which is higher than the AMD Radeon R5 M420's 6.800 GPixel/s. The NVIDIA part also has double the ROP count (16 versus 8).

Q: Which GPU supports the newer DirectX version?

A: The AMD Radeon R5 M420 supports DirectX 12 (11_1), while the NVIDIA GeForce GT 755M supports DirectX 12 (11_0). The AMD part has a slightly higher DirectX feature level.

Where Each One Wins

The NVIDIA GeForce GT 755M wins in every benchmark category measured. Its advantages are spread across multiple areas. In raw compute, the GT 755M delivers 783.4 GFLOPS of FP32 performance, which is 44% higher than the R5 M420's 544.0 GFLOPS. This makes the NVIDIA part better suited for GPU-accelerated applications like video encoding, image processing, and OpenCL compute tasks. The GT 755M's texture rate of 32.64 GTexel/s is nearly double the R5 M420's 17.00 GTexel/s, making it the clear winner for texture-heavy workloads and 3D rendering.

The GT 755M also wins decisively in memory bandwidth. With 86.40 GB/s available, it can feed its shading units much faster than the R5 M420's 16.00 GB/s. This is critical in modern games and applications that demand high data throughput. The NVIDIA part's 128-bit memory bus and GDDR5 memory are simply in a different class than the AMD part's 64-bit bus and DDR3 memory. For gaming at higher resolutions or with high-resolution textures, the GT 755M is the only viable option between these two.

The AMD Radeon R5 M420 does have one specification advantage: memory capacity. Its 4 GB of VRAM doubles the GT 755M's 2 GB. In scenarios where the application must hold a very large dataset in VRAM and the bandwidth requirement is low, the R5 M420 could theoretically have an edge. However, the data does not show any benchmark where this translates into a win. The R5 M420's lower clock speeds (780 MHz base, 850 MHz boost) and fewer processing units (320 shading units, 20 TMUs, 8 ROPs) hold it back. Its slot width is IGP, meaning it's integrated into the system, whereas the GT 755M is an MXM Module, a dedicated, replaceable graphics card.

For practical use, the GT 755M is the pick for gaming, GPU compute, and any workload that benefits from high memory bandwidth or high pixel/texture throughput. The R5 M420 is only suitable for basic display output, video playback, and extremely light 2D workloads where its larger memory buffer might be irrelevant. The benchmark data is unambiguous: the GT 755M is the superior GPU in every head-to-head comparison, and the R5 M420 offers no measured performance advantage anywhere.