NVIDIA GeForce 830M vs NVIDIA GeForce GT 645M Comparison

The Verdict

The NVIDIA GeForce GT 645M and NVIDIA GeForce 830M represent two different generations of laptop graphics, and the benchmark data shows a clear split in their strengths. The GT 645M, built on the Kepler architecture, wins the Vulkan test decisively, while the 830M, based on Maxwell, dominates the OpenCL test.

For users prioritizing Vulkan performance, the GT 645M is the choice, as it delivers a score of 4875 compared to the 830M's 3590, a 35.8% advantage. Conversely, the 830M is the better option for OpenCL workloads, posting 4324 against the GT 645M's 2680, a 38% lead in the opposite direction.

The average benchmark scores reflect this trade-off. The GT 645M has an average score of 4411, placing it in the 26th percentile of all GPUs, while the 830M averages 3957, sitting in the 24th percentile. Despite the GT 645M's higher average, the 830M is a closer rival to the AMD Radeon R5 M420 (3956, 0% delta) and NVIDIA GeForce GT 745M (3953, 0.1% delta), whereas the GT 645M sits near the NVIDIA GeForce 930M (4388, 0.5% delta) and Intel Iris Pro Graphics 5200 (4360, 1.2% delta).

The data also reveals a notable anomaly: the GT 645M's nearest rivals include the NVIDIA GeForce RTX 4070 GDDR6 (4335, 1.8% delta), meaning the GT 645M's average score is slightly above that of a modern high-end card. This is a statistical quirk of the database, not a practical comparison, and it should not be interpreted as equivalence in real-world gaming.

In summary, the GT 645M is the better choice for Vulkan-based applications and has a higher overall average benchmark score, while the 830M is the superior option for OpenCL compute tasks. Neither card is a clear winner across the board; the decision depends entirely on the workload.

FAQ

Q: Which GPU has the higher average benchmark score?

A: The NVIDIA GeForce GT 645M has a higher average benchmark score of 4411, placing it in the 26th percentile, while the NVIDIA GeForce 830M averages 3957, placing it in the 24th percentile.

Q: How do the two GPUs compare in the OpenCL benchmark?

A: The NVIDIA GeForce 830M wins the OpenCL test with a score of 4324, while the GT 645M scores 2680. This is a 38% delta in favor of the 830M.

Q: Which GPU performs better in Vulkan benchmarks?

A: The NVIDIA GeForce GT 645M wins the Vulkan test with a score of 4875, compared to the 830M's 3590. This represents a 35.8% advantage for the GT 645M.

Q: What are the closest rivals to each GPU based on average score?

A: For the GT 645M, the closest rival is the NVIDIA GeForce 930M (4388, 0.5% delta), followed by the Intel Iris Pro Graphics 5200 (4360, 1.2% delta). For the 830M, the closest rival is the AMD Radeon R5 M420 (3956, 0% delta), followed by the NVIDIA GeForce GT 745M (3953, 0.1% delta).

Q: Do both GPUs have the same memory configuration?

A: No. Both have 2 GB of DDR3 memory, but the GT 645M uses a 128-bit bus with a bandwidth of 28.80 GB/s, while the 830M uses a 64-bit bus with a bandwidth of 14.40 GB/s.

Q: What is the transistor density difference between the two chips?

A: The GT 645M's GK107 chip has a transistor density of 10.8M per mm², while the 830M's GM108 chip has a higher density of 13.2M per mm², despite having fewer total transistors.

Architecture Differences

The two GPUs are built on different NVIDIA architectures, which explains their divergent benchmark results. The GT 645M uses the Kepler architecture with the GK107 chip, fabricated on a 28 nm process at TSMC. The chip contains 1,270 million transistors on a die size of 118 mm², resulting in a transistor density of 10.8M per mm². Kepler was designed to offer strong graphics performance with efficient power usage, and the GT 645M's feature set reflects that.

The 830M, in contrast, uses the Maxwell architecture with the GM108 chip, also on a 28 nm process at TSMC. The GM108 chip contains 1,020 million transistors on a smaller die size of 77 mm², yielding a higher transistor density of 13.2M per mm². Maxwell was a major architectural shift for NVIDIA, focusing on improved compute efficiency and reduced power consumption per core. This explains why the 830M excels in OpenCL, which leverages compute throughput.

The shading unit counts also differ. The GT 645M has 384 shading units, 32 texture mapping units (TMUs), and 16 raster output units (ROPs). The 830M has 256 shading units, 16 TMUs, and 8 ROPs. Despite having fewer units, the 830M achieves higher pixel and texture rates per clock due to its higher clock speeds. Specifically, the 830M's pixel rate is 9.200 GPixel/s versus the GT 645M's 6.240 GPixel/s, while the texture rates are 18.40 GTexel/s and 24.96 GTexel/s, respectively.

The API support also differs. Both support DirectX 12 (11_0) and OpenGL 4.6, but the GT 645M supports Vulkan 1.2.175, while the 830M supports Vulkan 1.4. The newer Vulkan version on the 830M does not translate to better Vulkan performance in this case, as the GT 645M wins that benchmark.

Specification Differences

The recorded specifications show clear differences between the two GPUs beyond the architecture. The most significant divergence is in memory bandwidth. The GT 645M has a 128-bit memory bus with a bandwidth of 28.80 GB/s, while the 830M has a 64-bit bus with a bandwidth of 14.40 GB/s. Both use 2 GB of DDR3 memory at 900 MHz with 1800 Mbps effective speed, but the narrower bus halves the 830M's bandwidth.

The clock speeds also differ substantially. The GT 645M has a base clock of 709 MHz and a boost clock of 780 MHz, while the 830M runs at a base clock of 1082 MHz and a boost clock of 1150 MHz. The 830M's higher clocks partially compensate for its reduced core and memory resources.

The bus interface is another difference. The GT 645M uses PCIe 3.0 x16, while the 830M uses PCIe 3.0 x8. This means the GT 645M has twice the interface bandwidth available for data transfer, which can matter in bandwidth-sensitive tasks.

The power profiles are nearly identical. The GT 645M has a TDP of 32 W, and the 830M has a TDP of 33 W. Both are integrated into laptops (slot width is IGP) with no power connectors and portable-device-dependent display outputs.

The release dates differ by about 18 months. The GT 645M was released on 2012-09-30, while the 830M came out on 2014-03-11. The GT 645M's predecessor is the GeForce 500M, and its successor is the GeForce 700M. The 830M's predecessor is the GeForce 700M, and its successor is the GeForce 900M. Both are end-of-life products.

Head-to-Head Benchmarks

The head-to-head benchmark data shows a perfect split between the two GPUs. In the Geekbench OpenCL test, the 830M wins decisively with a score of 4324 against the GT 645M's 2680. This is a 38% delta in favor of the 830M, indicating that the Maxwell architecture's compute efficiency gives it a significant edge in OpenCL workloads.

In the Geekbench Vulkan test, the GT 645M reverses the result, scoring 4875 against the 830M's 3590. This is a 35.8% delta in favor of the GT 645M. The Kepler architecture, despite being older, clearly handles Vulkan operations more effectively than Maxwell in this comparison.

The average benchmark scores reflect these individual results. The GT 645M's average is 4411, which is higher than the 830M's 3957. However, this average is skewed by the GT 645M's strong Vulkan performance and the fact that it has three benchmark entries (Geekbench Metal, OpenCL, and Vulkan) versus the 830M's two (OpenCL and Vulkan). The GT 645M also has a Geekbench Metal score of 5679, which is not directly comparable since the 830M lacks that test.

When looking at the nearest rivals, the GT 645M's average score of 4411 is 0.5% ahead of the NVIDIA GeForce 930M (4388) and 1.2% ahead of the Intel Iris Pro Graphics 5200 (4360). The 830M's average score of 3957 is exactly even with the AMD Radeon R5 M420 (3956) and 0.1% behind the NVIDIA GeForce GT 745M (3953). This shows that the GT 645M sits in a slightly higher performance tier based on average scores.

Where Each One Wins

The data indicates distinct use-case advantages for each GPU. The GT 645M is the clear winner in Vulkan-based workloads, which are common in modern gaming and graphics applications that use the Vulkan API. Its 35.8% advantage over the 830M in this test is substantial and makes it the preferred choice for users running Vulkan titles or applications.

The GT 645M also has a higher average benchmark score overall (4411 versus 3957) and a higher percentile ranking (26th versus 24th). This suggests that, on aggregate, it may offer slightly better performance across a mix of workloads. Additionally, its wider 128-bit memory bus (28.80 GB/s bandwidth) and PCIe 3.0 x16 interface give it a theoretical advantage in memory-intensive tasks.

The 830M wins in OpenCL, which is used for general-purpose GPU computing, including tasks like video encoding, image processing, and scientific simulations. Its 38% lead in this test is even larger than the GT 645M's Vulkan advantage. This makes the 830M the better choice for compute-heavy applications that rely on OpenCL.

The 830M also benefits from a higher transistor density (13.2M per mm² versus 10.8M per mm²) and a more modern architecture (Maxwell versus Kepler), which contributes to its efficiency in compute tasks despite having fewer shading units (256 versus 384) and TMUs (16 versus 32).

In practice, the choice between these two GPUs depends on the specific software ecosystem. Users who prioritize Vulkan gaming should choose the GT 645M. Users who need OpenCL compute performance should choose the 830M. The 830M's lower memory bandwidth (14.40 GB/s) may limit it in memory-heavy scenarios, but its higher clock speeds (1082 MHz base, 1150 MHz boost) and architecture efficiency make it competitive where it matters. The GT 645M's Kepler architecture, with its older Vulkan version (1.2.175 versus 1.4), still outperforms in that specific test, showing that architecture generation is not the sole determinant of performance.