GPU Comparison

The NVIDIA GeForce GT 640 and NVIDIA GeForce 825M are both end-of-life mobile and desktop graphics solutions built on NVIDIA’s Kepler architecture, yet they target different segments of the market. The GT 640 is a desktop card from the GeForce 600 generation, while the 825M is an integrated mobile part from the GeForce 800M series. Benchmark data shows they are closely matched in raw compute, with the GT 640 holding a slight edge in the only shared test, but their underlying specifications and intended use cases diverge significantly. The following analysis breaks down these differences using only the provided facts.

FAQ

Q: Which GPU has a higher average benchmark score?

A: The NVIDIA GeForce 825M has a higher average benchmark score of 3694, compared to the GT 640’s 3210. This places the 825M in the 22nd percentile of all GPUs, while the GT 640 sits in the 20th percentile.

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

A: The GT 640 wins the head-to-head Geekbench OpenCL benchmark with a score of 3736, narrowly beating the 825M’s 3694. The performance difference is a marginal 1.1% in favor of the GT 640.

Q: What are the memory configurations of each card?

A: The GT 640 features 2 GB of DDR3 memory on a 128-bit bus, providing 28.51 GB/s of bandwidth. The 825M has 1024 MB of DDR3 memory on a 64-bit bus, yielding 14.40 GB/s, roughly half the bandwidth of the desktop part.

Q: Is there a difference in power consumption?

A: Yes, the GT 640 has a TDP of 65 W and requires a 250 W suggested PSU, while the 825M is rated at 33 W and has no suggested PSU listed. The 825M is an IGP (integrated graphics processor) with no power connectors, whereas the GT 640 is a single-slot card also without power connectors.

Q: Which GPU supports more display outputs?

A: The GT 640 offers 1x DVI, 1x HDMI 1.4a, and 1x DisplayPort 1.2 outputs. The 825M’s display outputs are listed as "Portable Device Dependent," meaning they vary based on the laptop it is integrated into.

Q: When were these GPUs released, and are they still in production?

A: The GT 640 was released on June 4, 2012, while the 825M arrived on January 26, 2014. Both are marked as end-of-life, with the GT 640 having a launch MSRP of 99 USD.

Architecture Differences

Both GPUs are built on TSMC’s 28 nm process, but they use different chips within the Kepler family. The GT 640 is based on the GK107 chip, while the 825M uses the GK208 chip. The GT 640 is labeled as "Kepler," whereas the 825M is designated "Kepler 2.0," indicating a slightly newer revision of the architecture. The transistor counts differ notably: the GT 640 packs 1,270 million transistors on a 118 mm² die, while the 825M has 1,020 million transistors on a smaller 87 mm² die. This results in a higher transistor density for the 825M at 11.7M / mm², compared to the GT 640’s 10.8M / mm².

The shading unit and texture mapping unit counts are identical: both have 384 shading units and 32 TMUs. However, the render output units (ROPs) differ, with the GT 640 featuring 16 ROPs and the 825M halving that to 8 ROPs. Clock speeds also separate them, the GT 640 has no listed base or boost clock, while the 825M runs at a base of 850 MHz and boost of 941 MHz. Memory clocks are similar, with the GT 640 at 891 MHz (1782 Mbps effective) and the 825M at 900 MHz (1800 Mbps effective). Neither GPU includes ray tracing or tensor cores, and both support DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175.

The bus interface differs as well: the GT 640 uses PCIe 3.0 x16, while the 825M is limited to PCIe 3.0 x8. The GT 640 is a discrete single-slot card, whereas the 825M is an IGP, meaning it is integrated into a mobile platform. The GT 640’s process node, foundry, and architecture are shared with the 825M, but the die size, transistor count, and ROP count create distinct performance profiles.

Where Each One Wins

The GT 640 wins in the only directly comparable benchmark, the Geekbench OpenCL test, with a 1.1% edge over the 825M. This suggests that for compute workloads using OpenCL, the desktop card holds a slight advantage. The GT 640 also offers a larger 2 GB memory capacity and a 128-bit bus, which doubles the memory bandwidth to 28.51 GB/s versus the 825M’s 14.40 GB/s. This makes the GT 640 better suited for tasks that are sensitive to memory throughput, such as higher-resolution textures or data-intensive compute applications. Its higher ROP count (16 vs. 8) also implies better pixel fill capabilities, though the pixel rate numbers are close: 7.216 GPixel/s for the GT 640 and 7.528 GPixel/s for the 825M.

The 825M, conversely, wins on efficiency and portability. Its TDP of 33 W is roughly half that of the GT 640’s 65 W, making it a better fit for thin-and-light laptops where power draw and heat are constrained. The 825M also has a higher average benchmark score (3694 vs. 3210) and a higher percentile ranking (22 vs. 20), indicating that in aggregate across all tests it performs slightly better than the GT 640 relative to the broader GPU landscape. The 825M’s higher clock speeds (850 MHz base, 941 MHz boost) and slightly higher texture rate (30.11 GTexel/s vs. 28.86 GTexel/s) give it a small edge in texture-bound scenarios, even with its narrower memory bus. For users prioritizing battery life and a compact form factor, the 825M is the clear choice, while the GT 640 appeals to those needing a discrete desktop card with more memory bandwidth.

Specification Differences

The two GPUs differ across several key specification fields. The GT 640 uses the GK107 chip, while the 825M uses GK208. The GT 640 is from the GeForce 600 generation, and the 825M is from the GeForce 800M generation. The GT 640 has 1,270 million transistors on a 118 mm² die, whereas the 825M has 1,020 million transistors on an 87 mm² die. Transistor density is 10.8M / mm² for the GT 640 and 11.7M / mm² for the 825M. The GT 640 has no listed base or boost clocks, while the 825M has a base clock of 850 MHz and a boost clock of 941 MHz. Memory size is 2 GB for the GT 640 versus 1024 MB for the 825M. Memory bus width is 128-bit for the GT 640 and 64-bit for the 825M. Memory bandwidth is 28.51 GB/s for the GT 640 and 14.40 GB/s for the 825M. ROPs are 16 for the GT 640 and 8 for the 825M. The TDP is 65 W for the GT 640 and 33 W for the 825M. The GT 640 is single-slot, while the 825M is an IGP. The bus interface is PCIe 3.0 x16 for the GT 640 and PCIe 3.0 x8 for the 825M. Display outputs are 1x DVI, 1x HDMI 1.4a, and 1x DisplayPort 1.2 for the GT 640, while the 825M’s outputs are portable device dependent. The GT 640 has a launch MSRP of 99 USD, while the 825M has no launch MSRP listed. Release dates are June 4, 2012, for the GT 640 and January 26, 2014, for the 825M. The GT 640’s predecessor and successor are GeForce 500 and GeForce 700, respectively, while the 825M’s are GeForce 700M and GeForce 900M.

Head-to-Head Benchmarks

The only direct comparison available is the Geekbench OpenCL test, where the GT 640 scores 3736 and the 825M scores 3694. This gives the GT 640 a win with a delta of 1.1%. While this is a slim margin, it is consistent with the GT 640’s wider memory bus and higher ROP count, which can aid certain compute tasks. The 825M, however, posts a higher average benchmark score of 3694 across all tests, compared to the GT 640’s 3210. This discrepancy suggests that the 825M performs better in other benchmark suites not shared between the two, likely due to its higher clock speeds and newer Kepler 2.0 architecture. The GT 640’s nearest rivals include the Intel Arc Pro B60 (avg 3182, delta 0.9%), NVIDIA Quadro P1000 (avg 3163, delta 1.5%), NVIDIA GeForce 920M (avg 3287, delta -2.3%), and NVIDIA GeForce GT 730M (avg 3316, delta -3.2%). The 825M’s nearest rivals are the NVIDIA GeForce GT 740M (avg 3717, delta -0.6%), NVIDIA Quadro 3000M (avg 3718, delta -0.6%), AMD Radeon HD 6770 (avg 3649, delta 1.2%), and NVIDIA GeForce GT 635M (avg 3740, delta -1.2%). In the OpenCL head-to-head, the GT 640’s 1.1% lead is smaller than the 2.3% gap between the GT 640 and the GeForce 920M, indicating that the two cards are very closely matched in raw compute performance. The 825M’s higher average score, despite losing the OpenCL test, points to strengths in other workloads that favor its boost clock of 941 MHz and higher texture rate of 30.11 GTexel/s. Overall, the data shows a near-tie in compute, with the GT 640 edging ahead in OpenCL but the 825M winning on aggregate performance and efficiency.