NVIDIA GeForce GT 640 vs NVIDIA GeForce GT 745M Comparison

Head-to-Head Benchmarks

The recorded data shows a clear split between these two Kepler-based NVIDIA parts. The GT 745M takes two of the three benchmark wins, and it does so decisively. In the Geekbench Vulkan test, the GT 745M scores 5502 against the GT 640's 3809, a 44.4% advantage. That is the single largest margin in this comparison, and it points to a substantial gap in modern API workloads.

The Geekbench Metal test also favors the GT 745M, with a score of 2777 versus 2086 for the GT 640. That 33.1% delta reinforces the pattern: when the workload leans on newer graphics APIs, the GT 745M pulls ahead by a wide margin. Both parts support DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175, so the API feature set is identical; the performance difference must come from elsewhere in the hardware.

The one reversal comes in Geekbench OpenCL. Here the GT 640 scores 3736, edging out the GT 745M's 3580. That is a 4.2% deficit for the GT 745M, a modest but real loss. OpenCL is a compute-oriented workload, and the data suggests the GT 640's higher raw throughput in certain compute patterns gives it a small advantage. The GT 640's FP32 rating of 692.7 GFLOPS versus the GT 745M's 421.6 GFLOPS likely explains this outcome, even though the GT 745M wins the overall average.

Looking at average benchmark scores, the GT 745M lands at 3953, while the GT 640 sits at 3210. That is a 23.1% gap in favor of the GT 745M. The percentile rankings tell a similar story: the GT 745M sits at the 23rd percentile among all GPUs, while the GT 640 is at the 20th. Neither part is a performance champion by modern standards, but the GT 745M consistently outranks its older sibling.

The nearest rivals in the database put both cards in context. The GT 745M's closest competitor is the AMD Radeon R5 M420, with an average score of 3956, a delta of only -0.1%. The NVIDIA GeForce 830M and Quadro K2000 are similarly close, at 3957 and 3964 respectively. The GT 640's rivals include the Intel Arc Pro B60 at 3182 (0.9% behind) and the NVIDIA Quadro P1000 at 3163 (1.5% behind). The GT 640 also trails the GeForce 920M by 2.3% and the GT 730M by 3.2%. These figures show that both cards are grouped tightly with their contemporaries, but the GT 745M occupies a slightly higher performance tier.

Where Each One Wins

The GT 745M is the clear winner for graphics-centric workloads. Its 44.4% lead in Vulkan and 33.1% lead in Metal indicate that it handles modern rendering pipelines more efficiently. If the target application uses Vulkan or Metal, the GT 745M is the stronger choice by a wide margin. This makes it the better option for games or applications that leverage these APIs, which includes most recent titles and many creative tools.

The GT 640 wins the OpenCL compute test by 4.2%. That suggests it has an edge in general-purpose compute tasks that use OpenCL, such as certain physics simulations, video encoding, or scientific calculations. The GT 640's higher pixel rate of 7.216 GPixel/s and texture rate of 28.86 GTexel/s, compared to the GT 745M's 4.392 GPixel/s and 17.57 GTexel/s, further support this. For raw rasterization throughput, the GT 640 is actually faster on paper. The issue is that modern benchmarks increasingly favor the newer API paths where the GT 745M excels.

For users who prioritize compatibility with current software, the GT 745M is the safer pick. Its Vulkan and Metal scores are dramatically better, and those APIs are becoming standard in both gaming and professional applications. The GT 640's OpenCL advantage is real but narrow, and it may not matter if the software in question has moved to Vulkan or Metal.

The GT 745M also wins on efficiency metrics that matter in practice. Its TDP is 45 W versus the GT 640's 65 W, and it is an IGP form factor designed for laptops, whereas the GT 640 is a single-slot desktop card. For mobile systems, the GT 745M is the only viable option of the two. For desktop builds where power draw is a concern, the GT 745M's lower TDP is a meaningful advantage even if the card itself is not typically sold as a desktop part.

Architecture Differences

Both GPUs share the same fundamental architecture. They use the GK107 chip, built on Kepler, manufactured by TSMC on a 28 nm process. The die size is identical at 118 mm², and the transistor count is the same at 1,270 million, giving a transistor density of 10.8M per mm². The shading units, texture mapping units, and render output units are all equal: 384 shading units, 32 TMUs, and 16 ROPs. Neither card has ray tracing cores or tensor cores, which was standard for this generation.

The key architectural differences lie in memory and clock behavior. The GT 745M uses GDDR5 memory with a 128-bit bus, running at 1000 MHz with 4 Gbps effective speed. This yields a bandwidth of 64.00 GB/s. The GT 640 uses DDR3 memory on the same 128-bit bus, running at 891 MHz with 1782 Mbps effective speed, producing only 28.51 GB/s of bandwidth. That is a 55.5% bandwidth deficit for the GT 640, which is a massive difference and likely the primary reason the GT 745M wins the Vulkan and Metal tests. Memory bandwidth is often the bottleneck in modern graphics workloads, and the GT 745M has more than double the bandwidth of the GT 640.

The memory size is the same at 2 GB, but the type difference is critical. GDDR5 is significantly faster than DDR3 per clock, and the GT 745M also runs its memory at a higher effective speed. The GT 640's memory clock of 891 MHz is lower than the GT 745M's 1000 MHz, compounding the bandwidth gap.

Other differences are more minor. The GT 745M is an IGP (integrated graphics processor) with portable device dependent display outputs, meaning it is soldered onto laptop motherboards. The GT 640 is a single-slot desktop card with 1x DVI, 1x HDMI 1.4a, and 1x DisplayPort 1.2 outputs, and it measures 145 mm or 5.7 inches in length. The GT 640 has no power connectors and a suggested PSU of 250 W, while the GT 745M's power connector situation is not specified. The GT 640 also has a higher TDP at 65 W, despite being architecturally similar, likely due to different clock behavior and desktop thermal headroom.

The release dates differ: the GT 640 launched in June 2012, while the GT 745M arrived in March 2013. Both are end-of-life products, and both share the same API support. The GT 745M belongs to the GeForce 700M generation, while the GT 640 belongs to the GeForce 600 generation. The predecessor and successor lines differ accordingly: the GT 745M follows the GeForce 600M and precedes the GeForce 800M, while the GT 640 follows the GeForce 500 and precedes the GeForce 700.

FAQ

Q: Which card is faster overall?

A: The GT 745M has a higher average benchmark score of 3953 versus 3210 for the GT 640, a 23.1% advantage. It also ranks at the 23rd percentile among all GPUs, compared to the GT 640's 20th percentile.

Q: Why does the GT 745M win Vulkan and Metal by such large margins?

A: The GT 745M has 64.00 GB/s of memory bandwidth thanks to GDDR5 memory, while the GT 640 has only 28.51 GB/s with DDR3. Modern APIs like Vulkan and Metal are sensitive to bandwidth, and the GT 745M's more than double bandwidth gives it a decisive edge.

Q: Does the GT 640 ever win a benchmark?

A: Yes, the GT 640 wins the Geekbench OpenCL test with a score of 3736 versus 3580 for the GT 745M, a 4.2% lead. Its higher FP32 rating of 692.7 GFLOPS and faster pixel and texture rates contribute to this compute advantage.

Q: Are these cards good for modern gaming?

A: No. Both sit near the bottom of the database rankings, with the GT 745M at the 23rd percentile and the GT 640 at the 20th. They are end-of-life products with no ray tracing or tensor cores, and their performance is far below what modern games typically require.

Q: Can I use the GT 640 in a desktop PC?

A: Yes, the GT 640 is a single-slot desktop card with 1x DVI, 1x HDMI 1.4a, and 1x DisplayPort 1.2 outputs. It requires no power connectors and has a suggested PSU of 250 W. The GT 745M, by contrast, is an IGP with portable device dependent outputs, so it is not a desktop part.

Q: What is the architectural difference between the two?

A: They share the same GK107 Kepler chip, 28 nm TSMC process, 118 mm² die size, 1,270 million transistors, and identical shading units, TMUs, and ROPs. The main differences are memory type (GDDR5 versus DDR3), memory bandwidth, TDP, and form factor.

The Verdict

The data points to a straightforward conclusion: the GT 745M is the better GPU for almost every use case. It wins two of three benchmarks, and its wins are decisive at 33.1% and 44.4%. Its average score is 23.1% higher, and it ranks higher in the database percentile. The only area where the GT 640 wins is OpenCL compute, and that win is a narrow 4.2%.

For anyone choosing between these two, the GT 745M is the recommended pick unless the workload is specifically OpenCL compute. Its GDDR5 memory provides 64.00 GB/s of bandwidth versus 28.51 GB/s, which is the defining hardware difference and the reason for its dominance in Vulkan and Metal. The GT 745M also consumes less power at 45 W versus 65 W, making it more efficient in addition to faster.

The GT 640 remains a viable option only in specific scenarios. Its higher FP32 throughput, pixel rate, and texture rate make it a better choice for compute-heavy tasks that use OpenCL. It also has the advantage of being a desktop card with standard display outputs, which means it can be installed in a desktop system without modification. The GT 745M is an IGP, so it is limited to laptops or systems with the appropriate socket.

In terms of launch pricing, the GT 640 had a launch MSRP of 99 USD, but that is historical data and does not change the performance picture. Both cards are end-of-life, so availability is limited to used or old stock. If both are available and compatibility allows, the GT 745M is the stronger performer in the vast majority of scenarios. The GT 640's only meaningful advantage is in OpenCL compute, and even there, the margin is small enough that real-world differences may be negligible.

The final recommendation: pick the GT 745M for graphics, gaming, or general use. Pick the GT 640 only if you need a desktop card for OpenCL compute and the GT 745M is not an option due to form factor constraints.

Specification Differences

| Specification | NVIDIA GeForce GT 745M | NVIDIA GeForce GT 640 |

|----------------|------------------------|-----------------------|

| Generation | GeForce 700M | GeForce 600 |

| Memory Type | GDDR5 | DDR3 |

| Memory Clock | 1000 MHz (4 Gbps effective) | 891 MHz (1782 Mbps effective) |

| Memory Bandwidth | 64.00 GB/s | 28.51 GB/s |

| Pixel Rate | 4.392 GPixel/s | 7.216 GPixel/s |

| Texture Rate | 17.57 GTexel/s | 28.86 GTexel/s |

| FP32 | 421.6 GFLOPS | 692.7 GFLOPS |

| TDP | 45 W | 65 W |

| Slot Width | IGP | Single-slot |

| Power Connectors | None specified | None |

| Suggested PSU | Not specified | 250 W |

| Display Outputs | Portable Device Dependent | 1x DVI, 1x HDMI 1.4a, 1x DisplayPort 1.2 |

| Length | Not specified | 145 mm (5.7 inches) |

| Release Date | March 2013 | June 2012 |

| Predecessor | GeForce 600M | GeForce 500 |

| Successor | GeForce 800M | GeForce 700 |

| Launch MSRP | Not specified | 99 USD |