GPU Comparison

The NVIDIA GeForce GT 645M and NVIDIA Quadro K3000M are both 28nm Kepler mobile parts from NVIDIA, but they target different segments within the laptop market. The GT 645M is a consumer GeForce chip, while the K3000M is a professional Quadro solution. The benchmark data available shows a clear performance gap, but the architectural differences and feature sets tell a more nuanced story for potential users.

FAQ

Q: Which GPU has the higher average benchmark score?

A: The NVIDIA Quadro K3000M has an average benchmark score of 4241, which is higher than the NVIDIA GeForce GT 645M's average score of 4411. However, this comparison is skewed because the GT 645M's average includes three benchmark tests (Geekbench Metal, OpenCL, and Vulkan), while the K3000M only has one OpenCL result.

Q: How do the two GPUs compare in the Geekbench OpenCL test?

A: The Quadro K3000M wins the head-to-head Geekbench OpenCL test with a score of 4241, while the GT 645M scores 2680. The delta percentage is -36.8, indicating the GT 645M is approximately 36.8% behind the K3000M in this specific workload.

Q: What are the memory bandwidth specifications for each GPU?

A: The GeForce GT 645M has a 128-bit bus with DDR3 memory, providing 28.80 GB/s of bandwidth. The Quadro K3000M uses a 256-bit bus with GDDR5 memory, delivering 89.60 GB/s, a more than threefold difference in memory throughput.

Q: Which GPU has more shading units and texture mapping units?

A: The Quadro K3000M has 576 shading units and 48 TMUs, while the GeForce GT 645M has 384 shading units and 32 TMUs. The Quadro also has double the ROPs, with 32 compared to the GT 645M's 16.

Q: What is the transistor count and die size difference between the two chips?

A: The GT 645M uses the GK107 chip with 1,270 million transistors on a 118 mm² die. The K3000M uses the larger GK104 chip with 3,540 million transistors on a 294 mm² die. The K3000M's chip has a higher transistor density at 12.0M / mm² compared to 10.8M / mm² for the GT 645M.

Q: What are the TDP and form factor differences?

A: The GT 645M has a TDP of 32 W and uses an IGP slot width, while the K3000M has a TDP of 75 W and uses an MXM Module slot width. The K3000M also uses an MXM-B (3.0) bus interface, whereas the GT 645M uses PCIe 3.0 x16.

Architecture Differences

Both GPUs share the Kepler architecture and are manufactured by TSMC on a 28 nm process node. The fundamental difference lies in the silicon used. The GeForce GT 645M is built on the GK107 chip, which is a smaller, more power-efficient design. The Quadro K3000M is built on the GK104 chip, a substantially larger and more complex processor.

The GK104 in the K3000M packs 3,540 million transistors across a 294 mm² die, while the GK107 in the GT 645M has 1,270 million transistors on a 118 mm² die. This gives the K3000M a 12.0M / mm² transistor density versus 10.8M / mm² for the GT 645M. The larger chip translates directly into more execution resources: the K3000M has 576 shading units, 48 TMUs, and 32 ROPs, compared to 384 shading units, 32 TMUs, and 16 ROPs for the GT 645M.

Memory architecture is another major divergence. The GT 645M uses 2 GB of DDR3 on a 128-bit bus, yielding 28.80 GB/s of bandwidth. The K3000M uses 2 GB of GDDR5 on a 256-bit bus, yielding 89.60 GB/s of bandwidth. Clock speeds differ as well; the GT 645M runs at 709 MHz base and 780 MHz boost, while the K3000M runs at a flat 654 MHz with no boost. Memory clock is also different: 900 MHz (1800 Mbps effective) for the GT 645M versus 700 MHz (2.8 Gbps effective) for the K3000M.

Both GPUs support DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175. Neither has ray tracing or tensor cores. The core feature sets are otherwise similar, but the K3000M is designated as a professional Quadro part, which historically implies different driver validation and software support. The GT 645M belongs to the GeForce 600M generation, while the K3000M belongs to the Quadro Kepler-M (Kx000M) generation.

Head-to-Head Benchmarks

The only direct head-to-head benchmark available is Geekbench OpenCL, and it produces a decisive result. The Quadro K3000M scores 4241, while the GeForce GT 645M scores 2680. That is a 36.8% deficit for the GT 645M. In raw compute terms, the K3000M's higher shading unit count and dramatically higher memory bandwidth explain this gap. The K3000M's FP32 performance is rated at 753.4 GFLOPS versus 599.0 GFLOPS for the GT 645M, a 25.8% advantage. Pixel rate is 7.848 GPixel/s for the K3000M versus 6.240 GPixel/s for the GT 645M, and texture rate is 31.39 GTexel/s versus 24.96 GTexel/s.

The GT 645M does have additional benchmark results that the K3000M lacks. In Geekbench Metal, the GT 645M scores 5679, and in Geekbench Vulkan, it scores 4875. These results are not comparable to anything from the K3000M, as no such tests were run for that GPU. The GT 645M's average benchmark score of 4411 is actually higher than the K3000M's 4241, but this is an artifact of the GT 645M having more test data, including the very high Metal score.

When looking at percentile rankings, the GT 645M sits at the 26th percentile of all GPUs, while the K3000M sits at the 25th percentile. These are nearly identical positions, despite the large gap in the OpenCL test. This suggests that the GT 645M's other benchmark results (Metal and Vulkan) pull its average up considerably, and that the K3000M's single OpenCL score is more representative of a low-midrange part.

The Verdict

The data shows a clear performance hierarchy. In the only directly comparable workload, Geekbench OpenCL, the Quadro K3000M is 36.8% faster than the GeForce GT 645M. The K3000M also has superior specifications across the board: more shading units, more TMUs, more ROPs, higher FP32 throughput, higher pixel rate, higher texture rate, and triple the memory bandwidth. The GK104 chip is nearly three times larger in transistor count and more than twice the die size.

The GeForce GT 645M is not without merit. Its much lower TDP of 32 W versus 75 W makes it far more suitable for thin-and-light notebooks. Its IGP form factor and PCIe 3.0 x16 interface are also more flexible for integration. The higher boost clock of 780 MHz (versus 654 MHz flat for the K3000M) partially offsets the architectural deficit, but not enough to close the gap in compute-heavy tasks.

Benchmark results indicate that the GT 645M's average score of 4411 is higher than the K3000M's 4241, but this is misleading. The GT 645M's Metal score of 5679 and Vulkan score of 4875 are not matched by any K3000M data. In the OpenCL test that both share, the K3000M wins decisively. Users looking at raw OpenCL performance should favor the K3000M. Users who need Metal or Vulkan support would have no data to compare, but the GT 645M at least has recorded results in those APIs.

Specification Differences

The two GPUs differ on nearly every specification field. The chip is GK107 for the GT 645M versus GK104 for the K3000M. Transistor count is 1,270 million versus 3,540 million. Die size is 118 mm² versus 294 mm². Transistor density is 10.8M / mm² versus 12.0M / mm².

Clock speeds: base clock is 709 MHz for the GT 645M versus 654 MHz for the K3000M. Boost clock is 780 MHz for the GT 645M versus 654 MHz (no boost) for the K3000M. Memory clock is 900 MHz (1800 Mbps effective) versus 700 MHz (2.8 Gbps effective). Memory bus width is 128 bit versus 256 bit. Memory bandwidth is 28.80 GB/s versus 89.60 GB/s.

Compute resources: shading units are 384 versus 576. TMUs are 32 versus 48. ROPs are 16 versus 32. Pixel rate is 6.240 GPixel/s versus 7.848 GPixel/s. Texture rate is 24.96 GTexel/s versus 31.39 GTexel/s. FP32 is 599.0 GFLOPS versus 753.4 GFLOPS.

Physical and power characteristics: TDP is 32 W versus 75 W. Slot width is IGP versus MXM Module. Bus interface is PCIe 3.0 x16 versus MXM-B (3.0). Memory type is DDR3 versus GDDR5. Memory size is the same at 2 GB for both.

Generation and release dates differ as well. The GT 645M is from the GeForce 600M generation, released on 2012-09-30. The K3000M is from the Quadro Kepler-M (Kx000M) generation, released on 2012-05-31. The GT 645M's predecessor is GeForce 500M and successor is GeForce 700M. The K3000M's predecessor is Quadro Fermi-M and successor is Quadro Maxwell-M.

Where Each One Wins

The Quadro K3000M wins in every compute and graphics throughput metric where data exists. Its 89.60 GB/s memory bandwidth is more than triple the GT 645M's 28.80 GB/s, which is critical for large datasets and high-resolution textures. Its 753.4 GFLOPS FP32 output is 25.8% higher than the GT 645M's 599.0 GFLOPS. The K3000M's 32 ROPs versus 16 ROPs means better fill-rate performance for pixel-heavy workloads. In the Geekbench OpenCL test, the K3000M's 4241 score exceeds the GT 645M's 2680 by 36.8%.

The GeForce GT 645M wins in power efficiency and integration flexibility. Its 32 W TDP is less than half of the K3000M's 75 W, making it suitable for systems with smaller cooling solutions. Its IGP slot width and PCIe 3.0 x16 interface are more standard for a wide range of laptops. The GT 645M also has recorded Metal and Vulkan benchmark scores (5679 and 4875, respectively), whereas the K3000M has no such data, suggesting the GT 645M may have broader API support in real-world usage.

The GT 645M's higher boost clock of 780 MHz versus the K3000M's flat 654 MHz gives it a per-clock advantage, but the K3000M's superior architecture more than compensates. For users running OpenCL-accelerated applications, the K3000M is the clear choice. For users in low-power environments or those who prioritize Metal and Vulkan workloads, the GT 645M may be more appropriate. The near-identical percentile rankings (26th versus 25th) suggest both GPUs occupy the same general performance tier, but the K3000M does so with more headroom in memory and compute resources.