NVIDIA GeForce 945M vs NVIDIA GeForce GTX 660 Comparison

FAQ

Q: How does the NVIDIA GeForce GTX 660 compare to the NVIDIA GeForce 945M in overall benchmark performance?

A: The GTX 660 has an average benchmark score of 9022, placing it in the 45th percentile of all GPUs. The 945M averages 8099, placing it in the 42nd percentile. The GTX 660 holds a clear performance lead in the recorded data.

Q: What is the largest performance gap between the two cards in the head-to-head tests?

A: In the Geekbench OpenCL test, the GTX 660 scores 11347 versus 8099 for the 945M, a delta of 40.1 percent in favor of the GTX 660. This is the only direct head-to-head benchmark recorded.

Q: Which GPU has a higher transistor density despite being on the same process node?

A: Both cards use a 28 nm process at TSMC. The 945M has a transistor density of 12.6M per mm², while the GTX 660 is slightly lower at 11.5M per mm², despite the GTX 660 having more total transistors.

Q: How do the memory subsystems differ between the two cards?

A: The GTX 660 uses 2 GB of GDDR5 memory on a 192-bit bus, delivering 144.2 GB/s of bandwidth. The 945M uses 2 GB of DDR3 memory on a 128-bit bus, delivering only 28.80 GB/s. This is a substantial bandwidth gap.

Q: What are the API support differences, particularly for Vulkan?

A: The GTX 660 supports Vulkan 1.2.175, while the 945M supports Vulkan 1.4. Both support DirectX 12 (11_0) and OpenGL 4.6. The 945M has a newer Vulkan implementation.

Q: Which card has a higher pixel rate and texture rate?

A: The GTX 660 leads in both: it achieves 20.64 GPixel/s and 82.56 GTexel/s, compared to the 945M's 16.32 GPixel/s and 40.80 GTexel/s. These figures reflect the GTX 660's higher ROP and TMU counts.

Where Each One Wins

The GTX 660 wins the only recorded head-to-head benchmark, the Geekbench OpenCL test, by a margin of 40.1 percent. That is a decisive victory, and it aligns with the broader specification sheet. The GTX 660 produces 1.981 TFLOPS of FP32 compute, while the 945M produces 1,305.6 GFLOPS. In raw throughput, texture work, and pixel fill, the GTX 660 is ahead across the board, making it the stronger choice for compute-heavy or fill-rate-limited workloads.

The 945M does not win any benchmark in the head-to-head comparison, but it does have specific advantages in deployment scenarios. It is an MXM module with no power connectors, a 75 W TDP, and no suggested PSU requirement, which makes it suited for portable or slim chassis where power delivery and space are constrained. The GTX 660, by contrast, is a dual-slot card with a 140 W TDP, a 1x 6-pin power connector, and a 300 W suggested PSU. The 945M also has a newer Vulkan API version (1.4 versus 1.2.175), which may matter for compatibility with the latest Vulkan applications.

In terms of efficiency per watt, the 945M delivers 1,305.6 GFLOPS at 75 W, while the GTX 660 delivers 1.981 TFLOPS at 140 W. The 945M's ratio of compute to power is higher, although the GTX 660 still has more absolute performance. For users who prioritize raw performance, the GTX 660 wins. For those who prioritize low power draw and module flexibility, the 945M has the edge.

Architecture Differences

The GTX 660 is built on the Kepler architecture using the GK106 chip, while the 945M uses the Maxwell architecture with the GM107 chip. Both are fabricated on a 28 nm process at TSMC, but the transistor counts differ: the GTX 660 packs 2,540 million transistors on a 221 mm² die, while the 945M has 1,870 million transistors on a 148 mm² die. The 945M has a higher transistor density per square millimeter (12.6M versus 11.5M), reflecting Maxwell's more compact design.

The GTX 660 has 960 shading units, 80 texture mapping units, and 24 ROPs. The 945M has 640 shading units, 40 TMUs, and 16 ROPs. This means the GTX 660 has 50 percent more shading units, double the TMUs, and 50 percent more ROPs. These differences directly explain the GTX 660's higher pixel rate (20.64 GPixel/s versus 16.32 GPixel/s) and texture rate (82.56 GTexel/s versus 40.80 GTexel/s).

Memory architecture also differs fundamentally. The GTX 660 uses GDDR5 memory across a 192-bit bus, while the 945M uses DDR3 across a 128-bit bus. The memory clock speeds reflect this: the GTX 660 runs at 1502 MHz with 6 Gbps effective, while the 945M runs at 900 MHz with 1800 Mbps effective. The resulting bandwidth gap is enormous: 144.2 GB/s versus 28.80 GB/s, a roughly fivefold difference.

Both cards lack dedicated ray tracing cores and tensor cores. The GTX 660 supports DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175. The 945M supports DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.4. The 945M's higher Vulkan version is the only API advantage it holds.

Specification Differences

The two cards differ in nearly every measurable specification. The GTX 660 has base and boost clocks of 980 MHz and 1032 MHz, while the 945M runs at 928 MHz base and 1020 MHz boost. The GTX 660's memory clock is 1502 MHz with 6 Gbps effective, versus 900 MHz with 1800 Mbps effective for the 945M.

Memory size is the same at 2 GB, but the type, bus width, and bandwidth differ: GDDR5 on a 192-bit bus for 144.2 GB/s versus DDR3 on a 128-bit bus for 28.80 GB/s. The GTX 660 has 960 shading units, 80 TMUs, and 24 ROPs; the 945M has 640 shading units, 40 TMUs, and 16 ROPs.

Pixel rate is 20.64 GPixel/s for the GTX 660 versus 16.32 GPixel/s for the 945M. Texture rate is 82.56 GTexel/s versus 40.80 GTexel/s. FP32 compute is 1.981 TFLOPS versus 1,305.6 GFLOPS.

Power and physical specifications diverge sharply. The GTX 660 has a TDP of 140 W, is dual-slot, requires a 1x 6-pin power connector, and a 300 W suggested PSU. The 945M has a TDP of 75 W, is an MXM module, requires no power connectors, and has no suggested PSU. The GTX 660 uses a PCIe 3.0 x16 interface, while the 945M uses MXM-B (3.0). Display outputs also differ: the GTX 660 has 2x DVI, 1x HDMI 1.4a, and 1x DisplayPort 1.2, while the 945M's outputs are portable device dependent. The GTX 660 is 241 mm long (9.5 inches); the 945M has no recorded dimensions.

The GTX 660 was released on 2012-09-05 with a launch MSRP of 229 USD. The 945M was released on 2015-10-26 with no launch MSRP recorded. Both are end-of-life products. The GTX 660's predecessor is the GeForce 500 series and its successor is the GeForce 700 series. The 945M's predecessor is the GeForce 800M and its successor is the GeForce 10 Mobile.

Head-to-Head Benchmarks

The database records a single head-to-head benchmark between these two GPUs: Geekbench OpenCL. The GTX 660 scores 11347, while the 945M scores 8099. The GTX 660 wins with a delta of 40.1 percent. That is a commanding lead, and it is consistent with the GTX 660's substantial advantages in shading units, texture units, ROPs, and memory bandwidth.

In the broader benchmark context, the GTX 660's average score of 9022 places it near the NVIDIA TITAN V CEO Edition (9037, delta of -0.2 percent) and the NVIDIA GeForce GTX 560 (9058, delta of -0.4 percent). It is also ahead of the AMD Radeon 550X (8918, delta of 1.2 percent) and the AMD Radeon Pro WX 5100 (8863, delta of 1.8 percent). This means the GTX 660 sits in a competitive midrange tier, trading blows with much newer and more expensive parts.

The 945M's average score of 8099 places it near the NVIDIA GRID K2 (8080, delta of 0.2 percent) and the NVIDIA GeForce GTX 650 Ti Boost (8067, delta of 0.4 percent). It trails the AMD Radeon R9 M360 (8129, delta of -0.4 percent) and the NVIDIA GeForce GTX 950M (8135, delta of -0.4 percent). The 945M is thus clustered tightly with other mobile-oriented and older desktop parts, sitting just below the GTX 660's tier in the database's percentile ranking (42nd versus 45th).

The Geekbench OpenCL result is the only direct measurement, but the specification deltas support the same conclusion. The GTX 660's texture rate is more than double the 945M's, its pixel rate is 26 percent higher, and its memory bandwidth is over five times higher. In any workload that stresses memory bandwidth or texture fill, the GTX 660 should maintain a similar or larger lead. The 945M's only recorded advantages are a newer Vulkan version, lower power draw, and a smaller physical footprint. For raw benchmark performance, the GTX 660 is the clear winner.