NVIDIA GeForce GT 645M vs NVIDIA GeForce GT 745M Comparison

Head-to-Head Benchmarks

The benchmark data paints a split picture between these two mobile GPUs. The GeForce GT 645M and GT 745M trade blows depending on the test, with each claiming a victory in different workloads.

The most dramatic difference appears in the Geekbench Metal test. Here, the GT 645M scores 5,679 points compared to the GT 745M's 2,777 points. That is a massive 104.5% advantage for the older card, making it more than twice as fast in this specific API. This is the single biggest margin in any benchmark between the two, and it is a decisive win for the GT 645M.

However, the GT 745M strikes back in the other two tests. In Geekbench OpenCL, the GT 745M scores 3,580 points against the GT 645M's 2,680 points, a 25.1% lead. The margin is smaller than the Metal gap, but it is still a clear victory. The GT 745M also wins the Geekbench Vulkan test, scoring 5,502 points versus 4,875 points for the GT 645M, a narrower 11.4% edge.

Looking at the overall average benchmark score, the GT 645M comes out ahead. Its average score is 4,411 points, while the GT 745M sits at 3,953 points. This puts the GT 645M in the 26th percentile of all GPUs, while the GT 745M lands in the 23rd percentile. The difference in average score is about 458 points, which is meaningful but not overwhelming.

The nearest rivals in the database provide context for these numbers. The GT 645M's closest competitor is the AMD Radeon R7 M260, which scores 4,499 points, putting it 1.9% ahead. The NVIDIA GeForce 930M sits just 0.5% behind the GT 645M with 4,388 points, and the Intel Iris Pro Graphics 5200 is 1.2% behind with 4,360 points. Interestingly, the NVIDIA GeForce RTX 4070 GDDR6 appears in the GT 645M's rival list with a score of 4,335 points, which is 1.8% lower, a reminder that these are aggregate scores across very different test conditions.

For the GT 745M, the rival field is tighter. The AMD Radeon R5 M420 scores 3,956 points, just 0.1% ahead, and the NVIDIA GeForce 830M also scores 3,957 points, also 0.1% ahead. The NVIDIA Quadro K2000 is 0.3% ahead with 3,964 points, while the NVIDIA Quadro 2000D trails by 0.6% with 3,930 points. These sub-1% gaps mean the GT 745M is essentially tied with its closest competitors in aggregate performance.

Architecture Differences

Both GPUs share the same fundamental architecture, which makes their performance differences more interesting. Both use the GK107 chip, built on NVIDIA's Kepler architecture, and both are manufactured by TSMC on a 28 nm process node. The transistor count is identical at 1,270 million, and the die size matches at 118 mm². This results in the same transistor density of 10.8M per mm².

The core configuration is also identical. Both GPUs have 384 shading units, 32 texture mapping units, and 16 raster output units. Neither has any ray tracing or tensor cores, as expected for this generation. The pixel and texture rates, however, differ. The GT 645M achieves 6.240 GPixel/s and 24.96 GTexel/s, while the GT 745M is lower at 4.392 GPixel/s and 17.57 GTexel/s. This suggests the GT 645M runs at higher clock speeds for these operations.

The floating-point performance tells a similar story. The GT 645M delivers 599.0 GFLOPS of FP32 performance, while the GT 745M delivers 421.6 GFLOPS. This is a significant gap in raw compute throughput, and it explains why the GT 645M wins in some compute-heavy tests.

The memory subsystem is where the two cards diverge most clearly. The GT 645M uses 2 GB of DDR3 memory on a 128-bit bus, running at 900 MHz with 1800 Mbps effective speed. This yields a bandwidth of 28.80 GB/s. The GT 745M also has 2 GB, but it uses GDDR5 memory on the same 128-bit bus. Its memory runs at 1000 MHz with 4 Gbps effective speed, more than doubling the bandwidth to 64.00 GB/s. This is a major architectural difference: the GT 745M has 122% more memory bandwidth than the GT 645M.

The power envelopes differ as well. The GT 645M has a TDP of 32 W, while the GT 745M is rated at 45 W. Both are integrated into the motherboard as IGP parts with portable-device-dependent display outputs, and both use a PCIe 3.0 x16 bus interface. The GT 645M has no power connectors, while the GT 745M's connector status is not recorded.

The API support is identical: DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175. The GT 645M belongs to the GeForce 600M generation, released in late September 2012, with the GeForce 500M as its predecessor and the GeForce 700M as its successor. The GT 745M belongs to the GeForce 700M generation, released about six months later in early April 2013, with the GeForce 600M as its predecessor and the GeForce 800M as its successor. Both are end-of-life products.

The Verdict

The data shows a clear split personality between these two GPUs. If your workload leans on Metal, the GT 645M is the obvious choice: it is 104.5% faster in that test, a margin that dominates any other comparison. The GT 645M also holds the higher average benchmark score at 4,411 versus 3,953, and it lands higher in the percentile ranking.

But the GT 745M is not without merit. It wins in OpenCL by 25.1% and in Vulkan by 11.4%, and its GDDR5 memory provides 64.00 GB/s of bandwidth versus 28.80 GB/s for the GT 645M. For applications that are bandwidth-sensitive, the GT 745M has a structural advantage that the raw compute numbers do not capture.

The choice depends on which API or workload you prioritize. For Metal-based applications, the GT 645M is the stronger part by a wide margin. For OpenCL or Vulkan workloads, the GT 745M takes the lead. The aggregate scores suggest the GT 645M is the better overall performer, but the GT 745M's wins in two of three tests show it is competitive in the right circumstances.

Specification Differences

The two GPUs differ in several specification fields:

• Memory Type: The GT 645M uses DDR3, while the GT 745M uses GDDR5.
• Memory Clock: The GT 645M runs at 900 MHz with 1800 Mbps effective, while the GT 745M runs at 1000 MHz with 4 Gbps effective.
• Memory Bandwidth: The GT 645M has 28.80 GB/s, while the GT 745M has 64.00 GB/s.
• Pixel Rate: The GT 645M achieves 6.240 GPixel/s, while the GT 745M achieves 4.392 GPixel/s.
• Texture Rate: The GT 645M achieves 24.96 GTexel/s, while the GT 745M achieves 17.57 GTexel/s.
• FP32 Performance: The GT 645M delivers 599.0 GFLOPS, while the GT 745M delivers 421.6 GFLOPS.
• TDP: The GT 645M is rated at 32 W, while the GT 745M is rated at 45 W.
• Generation: The GT 645M is in the GeForce 600M series, while the GT 745M is in the GeForce 700M series.
• Release Date: The GT 645M launched in late September 2012, while the GT 745M launched in early April 2013.
• Predecessor/Successor: The GT 645M succeeds the GeForce 500M and is succeeded by the GeForce 700M; the GT 745M succeeds the GeForce 600M and is succeeded by the GeForce 800M.
• Base/Boost Clocks: The GT 645M has recorded base and boost clocks of 709 MHz and 780 MHz, while the GT 745M has no recorded base or boost clocks.

FAQ

Q: Which GPU has more memory bandwidth?

A: The GT 745M has 64.00 GB/s of bandwidth, which is more than double the GT 645M's 28.80 GB/s.

Q: Which GPU wins in the Geekbench Metal test?

A: The GT 645M wins decisively, scoring 5,679 points versus 2,777 points for the GT 745M, a 104.5% advantage.

Q: Are these GPUs based on the same architecture?

A: Yes, both use the GK107 chip on NVIDIA's Kepler architecture, manufactured on TSMC's 28 nm process with 1,270 million transistors and a 118 mm² die size.

Q: Which GPU has a higher FP32 compute throughput?

A: The GT 645M delivers 599.0 GFLOPS, while the GT 745M delivers 421.6 GFLOPS, making the GT 645M about 42% faster in raw FP32.

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

A: The GT 645M has an average score of 4,411 points, while the GT 745M has an average score of 3,953 points.

Q: How does the GT 745M compare to its closest rivals?

A: The GT 745M is essentially tied with its nearest rivals: the AMD Radeon R5 M420 is 0.1% ahead, the NVIDIA GeForce 830M is 0.1% ahead, the NVIDIA Quadro K2000 is 0.3% ahead, and the NVIDIA Quadro 2000D is 0.6% behind.

Where Each One Wins

The GT 645M wins in compute-heavy and Metal-based scenarios. Its FP32 throughput of 599.0 GFLOPS is significantly higher than the GT 745M's 421.6 GFLOPS, which explains its dominant Metal result. The GT 645M also has higher pixel and texture rates, making it better suited for tasks that rely on raw shading and texturing speed. Its lower TDP of 32 W versus 45 W also makes it the more power-efficient option.

The GT 745M wins in bandwidth-dependent and non-Metal API workloads. Its GDDR5 memory at 64.00 GB/s gives it a massive bandwidth advantage, which likely drives its 25.1% OpenCL win and 11.4% Vulkan win. For applications that move large amounts of data, the GT 745M is the better fit. It also has the higher effective memory clock at 4 Gbps versus 1800 Mbps.

In practical terms, the GT 645M is the pick for Metal-centric workflows and for users who want higher compute throughput per watt. The GT 745M is the pick for OpenCL or Vulkan workloads and for scenarios where memory bandwidth is the limiting factor. The aggregate data favors the GT 645M, but the GT 745M's two benchmark wins show it is the more balanced choice for mixed API usage.