AMD Radeon HD 6770 vs NVIDIA GeForce GT 645M Comparison

Head-to-Head Benchmarks

The only directly comparable benchmark between the NVIDIA GeForce GT 645M and the AMD Radeon HD 6770 is Geekbench OpenCL. In this test, the AMD Radeon HD 6770 records a score of 3649, while the NVIDIA GeForce GT 645M reaches 2680. The delta is 26.6% in favor of the AMD part, making it the clear winner in this single head-to-head comparison. The database records 0 wins for the NVIDIA GPU and 1 win for the AMD GPU.

This 26.6% advantage in OpenCL compute performance is substantial. Looking at the broader context, the AMD Radeon HD 6770 sits at the 22nd percentile of all GPUs, which puts it slightly above the NVIDIA GeForce GT 645M at the 26th percentile (note: higher percentile is better in this database). Despite the percentile difference appearing small, the raw score gap is significant.

The NVIDIA GeForce GT 645M has a higher average benchmark score of 4411 across all its recorded tests, which includes Geekbench Metal (5679), Geekbench Vulkan (4875), and Geekbench OpenCL (2680). The AMD Radeon HD 6770 only has a single recorded Geekbench OpenCL score of 3649, so its average benchmark score is identical to that single result.

When examining the nearest rivals in the database, the AMD Radeon HD 6770's OpenCL score of 3649 places it just 0.6% above the NVIDIA GeForce GTX 1050 (3629) and 0.9% above the NVIDIA GeForce GT 735M (3616). It trails the NVIDIA GeForce 825M by 1.2% (3694) and leads the NVIDIA RTX 5000 Mobile Ada Generation by 1.5% (3596). These tight margins suggest that the HD 6770's compute performance is competitive with a cluster of much newer mobile GPUs.

The NVIDIA GeForce GT 645M, on the other hand, shows an average score of 4411, which is 0.5% above the NVIDIA GeForce 930M (4388), 1.2% above the Intel Iris Pro Graphics 5200 (4360), and 1.8% above the NVIDIA GeForce RTX 4070 GDDR6 (4335). It falls 1.9% short of the AMD Radeon R7 M260 (4499). The GT 645M's strength clearly lies in its Metal and Vulkan results, where it posts scores of 5679 and 4875 respectively, far exceeding its own OpenCL result.

Architecture Differences

The two GPUs come from fundamentally different architectural eras. The NVIDIA GeForce GT 645M is built on the Kepler architecture using the GK107 chip, manufactured on a 28 nm process at TSMC. It packs 1,270 million transistors into a die size of 118 mm², yielding a transistor density of 10.8 million per square millimeter. In contrast, the AMD Radeon HD 6770 uses the TeraScale 2 architecture with the Juniper chip, fabricated on a 40 nm process, also at TSMC. It contains 1,040 million transistors across a larger 166 mm² die, resulting in a lower density of 6.3 million per square millimeter.

The NVIDIA part belongs to the GeForce 600M generation and succeeds the GeForce 500M line, with the GeForce 700M as its successor. The AMD card is part of the Northern Islands (HD 6700) generation, succeeding the Evergreen family and followed by Southern Islands. The process node difference is notable: 28 nm versus 40 nm gives the Kepler chip a distinct density and efficiency advantage.

Clock behavior differs significantly. The GT 645M has a base clock of 709 MHz and a boost clock of 780 MHz, a feature the HD 6770 lacks entirely, as it has no recorded base or boost clocks. Memory clocks also diverge: the NVIDIA GPU runs its memory at 900 MHz with 1800 Mbps effective data rate, while the AMD card's memory runs at 1200 MHz with 4.8 Gbps effective. This memory clock difference directly impacts bandwidth, as detailed in the specification section.

Compute resources are organized very differently. The GT 645M has 384 shading units, 32 texture mapping units, and 16 raster operation pipelines. The HD 6770 has 800 shading units, 40 TMUs, and 16 ROPs. Despite having fewer shading units, the NVIDIA part is built around Kepler's architecture, which groups them into SMX units designed for efficient scheduling. The AMD part's TeraScale 2 uses a VLIW design with 800 stream processors.

API support also separates the two. The GT 645M supports DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175. The HD 6770 supports DirectX 11.2 (11_0) and OpenGL 4.4, but has no Vulkan support recorded. This means the NVIDIA GPU can run modern Vulkan titles and newer DirectX 12 workloads, while the AMD card is limited to older API levels.

Where Each One Wins

The AMD Radeon HD 6770 wins decisively in raw OpenCL compute throughput. Its 26.6% lead over the GT 645M in that specific test indicates that workloads leveraging OpenCL for general-purpose computation, such as physics simulations, video encoding, or data-parallel tasks, will run noticeably faster on the AMD card. The HD 6770 also posts a much higher pixel rate (13.60 GPixel/s versus 6.240 GPixel/s) and texture rate (34.00 GTexel/s versus 24.96 GTexel/s), suggesting it can fill framebuffers and sample textures more quickly in fill-rate-bound scenarios.

The NVIDIA GeForce GT 645M, however, shows its strengths in other areas. Its average benchmark score of 4411 is higher than the AMD part's 3649, driven by strong Metal and Vulkan results. For applications that use Apple's Metal API, the GT 645M achieves 5679, a figure that dwarfs its own OpenCL score and indicates excellent performance in Metal-optimized software. Similarly, its Vulkan score of 4875 shows solid capability in Vulkan-based games and compute workloads, something the HD 6770 cannot do at all since it lacks Vulkan support.

The GT 645M also wins on efficiency and integration. Its 32 W TDP is dramatically lower than the HD 6770's 108 W, making it suitable for thin-and-light laptops where the AMD card's dual-slot cooler and 6-pin power connector would be impractical. The NVIDIA GPU is an IGP (integrated graphics processor) with no power connectors, while the AMD card requires a 300 W suggested PSU and a dual-slot footprint.

For gamers, the choice depends on the API and platform. On modern systems running Vulkan titles, the GT 645M is the only option. On older DirectX 11 workloads, the HD 6770's higher fill rates and compute throughput give it an edge. For compute tasks via OpenCL, the AMD card is clearly superior. For users prioritizing portability and low power draw, the GT 645M is the obvious pick.

FAQ

Q: Which GPU has the higher Geekbench OpenCL score?

A: The AMD Radeon HD 6770 scores 3649 in Geekbench OpenCL, which is 26.6% higher than the NVIDIA GeForce GT 645M's score of 2680.

Q: Does the AMD Radeon HD 6770 support Vulkan?

A: No, the HD 6770 has no Vulkan support recorded in the database. The NVIDIA GeForce GT 645M supports Vulkan 1.2.175.

Q: How do their average benchmark scores compare?

A: The GT 645M has an average benchmark score of 4411 across three tests (Metal, OpenCL, Vulkan), while the HD 6770 has an average of 3649 from its single OpenCL result.

Q: What is the power consumption difference?

A: The GT 645M has a 32 W TDP and requires no power connectors, while the HD 6770 has a 108 W TDP and needs a 6-pin power connector with a suggested 300 W PSU.

Q: Which GPU has better DirectX support?

A: The GT 645M supports DirectX 12 (11_0), whereas the HD 6770 is limited to DirectX 11.2 (11_0).

Q: How does the memory configuration differ?

A: The GT 645M uses 2 GB of DDR3 on a 128-bit bus with 28.80 GB/s bandwidth. The HD 6770 uses 1 GB of GDDR5 on a 128-bit bus with 76.80 GB/s bandwidth.

Specification Differences

The two GPUs differ across nearly every core specification. The NVIDIA GeForce GT 645M uses the GK107 chip on a 28 nm process, while the AMD Radeon HD 6770 uses the Juniper chip on a 40 nm process. Transistor counts are 1,270 million versus 1,040 million, and die sizes are 118 mm² versus 166 mm², giving densities of 10.8M per mm² and 6.3M per mm² respectively.

Clock speeds show the NVIDIA part with a base of 709 MHz and boost of 780 MHz, while the AMD card has no recorded base or boost clock. Memory clocks are 900 MHz (1800 Mbps effective) for the GT 645M and 1200 MHz (4.8 Gbps effective) for the HD 6770. Memory capacity is 2 GB DDR3 versus 1 GB GDDR5, both on a 128-bit bus, but bandwidth differs sharply: 28.80 GB/s versus 76.80 GB/s.

Compute resources: the GT 645M has 384 shading units, 32 TMUs, and 16 ROPs. The HD 6770 has 800 shading units, 40 TMUs, and 16 ROPs. Pixel rates are 6.240 GPixel/s versus 13.60 GPixel/s, and texture rates are 24.96 GTexel/s versus 34.00 GTexel/s. FP32 performance is 599.0 GFLOPS versus 1,360.0 GFLOPS.

Power and physical design: the GT 645M is an IGP with 32 W TDP and no power connectors. The HD 6770 is dual-slot with 108 W TDP, a 6-pin connector, a suggested 300 W PSU, and a length of 198 mm (7.8 inches). Bus interfaces are PCIe 3.0 x16 for the NVIDIA part and PCIe 2.0 x16 for the AMD part.

Display outputs: the GT 645M is portable-device dependent, while the HD 6770 offers 2x DVI, 1x HDMI 1.3a, and 2x mini-DisplayPort 1.1. API support: the GT 645M hits DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175; the HD 6770 reaches DirectX 11.2 (11_0) and OpenGL 4.4 with no Vulkan. Release dates are September 2012 for the NVIDIA part and January 2011 for the AMD part. The AMD card had a launch MSRP of 129 USD.