AMD Radeon Vega 3 vs NVIDIA GeForce GT 645M Comparison

The NVIDIA GeForce GT 645M and AMD Radeon Vega 3 are both end-of-life integrated-class graphics solutions, but they represent vastly different design philosophies and eras. The GT 645M is a 28 nm Kepler part from 2012, while the Vega 3 is a 12 nm GCN 5.0 IGP from 2019. Benchmark results show a split decision: the NVIDIA part wins two of three head-to-head tests, yet the AMD part claims a decisive victory in the third. The average benchmark scores are close—4411 for the GT 645M versus 4268 for the Vega 3—placing both in the bottom quartile of all GPUs (26th and 25th percentiles, respectively). This page breaks down exactly where each part excels and where it falls short, using only the data provided.

Head-to-Head Benchmarks

The most striking result is in the Geekbench Metal test, where the NVIDIA GeForce GT 645M scores 5679 against the AMD Radeon Vega 3's 4880. That is a 16.4% advantage for the NVIDIA part, making it the single largest margin in any test. The GT 645M also wins the Vulkan test, scoring 4875 versus 3961, a 23.1% lead. These two wins give the GT 645M a 2–1 victory in the head-to-head series. The Vulkan margin is particularly notable, as it shows the older Kepler architecture maintaining a strong lead in a modern API workload.

However, the AMD Radeon Vega 3 strikes back hard in the Geekbench OpenCL test. Here, the Vega 3 scores 3963 while the GT 645M manages only 2680. That is a 32.4% deficit for the NVIDIA part, meaning the Vega 3 outperforms it by nearly a third in this compute-oriented benchmark. This is the single biggest delta in either direction across all three tests. The OpenCL result flips the overall narrative: while NVIDIA wins on raw graphics APIs, AMD’s newer GCN 5.0 architecture shows clear superiority in general-purpose compute.

Looking at the average benchmark scores, the GT 645M's 4411 average edges out the Vega 3's 4268 by roughly 3.4%. This aggregate figure masks the extreme variance between test types. The GT 645M's nearest rivals in the database include the NVIDIA GeForce 930M (avg 4388, deltaPct 0.5%) and the Intel Iris Pro Graphics 5200 (avg 4360, deltaPct 1.2%), indicating it sits in a tightly packed cluster of similarly performing parts. The Vega 3's nearest rivals include the NVIDIA GeForce GTX 460M (avg 4282, deltaPct -0.3%) and the AMD FirePro W2100 (avg 4295, deltaPct -0.6%), showing it too is surrounded by comparable hardware. Interestingly, both parts are listed with the NVIDIA GeForce RTX 4070 GDDR6 as a nearest rival—the GT 645M is 1.8% above it, while the Vega 3 is 1.5% below it—which is an artifact of the database's clustering rather than a meaningful comparison.

FAQ

Q: Which GPU wins more head-to-head benchmark tests?

A: The NVIDIA GeForce GT 645M wins two of the three tests—Geekbench Metal (5679 vs 4880) and Geekbench Vulkan (4875 vs 3961)—while the AMD Radeon Vega 3 wins only Geekbench OpenCL (3963 vs 2680).

Q: What is the largest performance gap between the two?

A: The biggest delta is in Geekbench OpenCL, where the AMD Radeon Vega 3 leads by 32.4%. The next largest is in Vulkan, where NVIDIA leads by 23.1%.

Q: How do their average benchmark scores compare?

A: The NVIDIA GeForce GT 645M has an average benchmark score of 4411, while the AMD Radeon Vega 3 averages 4268. This places them at the 26th and 25th percentiles of all GPUs, respectively.

Q: Are there any notable rival comparisons for each card?

A: The GT 645M is 0.5% ahead of the NVIDIA GeForce 930M and 1.2% ahead of the Intel Iris Pro Graphics 5200. The Vega 3 is 0.3% behind the NVIDIA GeForce GTX 460M and 0.6% behind the AMD FirePro W2100.

Q: Which part has higher raw compute throughput (FP32)?

A: The NVIDIA GeForce GT 645M delivers 599.0 GFLOPS FP32, which is higher than the AMD Radeon Vega 3's 422.4 GFLOPS. However, the Vega 3 also supports FP16 at 844.8 GFLOPS (2:1), which the GT 645M does not list.

Q: What are their production statuses?

A: Both are listed as end-of-life products. The GT 645M was succeeded by the GeForce 700M, and the Vega 3 was succeeded by the Vega II IGP.

The Verdict

The data supports a split decision based on workload type. For users prioritizing graphics API performance—specifically Metal and Vulkan—the NVIDIA GeForce GT 645M is the clear choice. It holds a 16.4% lead in Metal and a 23.1% lead in Vulkan, making it the stronger pick for gaming or rendering tasks that leverage these APIs. The GT 645M also has a higher average benchmark score (4411 vs 4268), suggesting slightly better overall consistency across tested workloads.

For compute-heavy tasks that rely on OpenCL, the AMD Radeon Vega 3 is unequivocally superior. Its 32.4% advantage in OpenCL is the largest margin in any test, and it also offers FP16 support (844.8 GFLOPS), which the GT 645M lacks entirely. This makes the Vega 3 the better option for developers or users running general-purpose GPU compute workloads that can utilize OpenCL or half-precision arithmetic.

Neither part is a performance champion—both sit at the 25th–26th percentile of all GPUs. The GT 645M's wins in Metal and Vulkan are significant, but the Vega 3's OpenCL dominance is equally decisive. If forced to pick based on the data alone, the GT 645M's two-out-of-three win record and higher average score give it a slight edge for general use, but only if OpenCL performance is not a primary consideration.

Specification Differences

The two GPUs differ fundamentally in nearly every hardware specification. The NVIDIA GeForce GT 645M uses a 28 nm process node from TSMC, while the AMD Radeon Vega 3 uses a 12 nm node from GlobalFoundries. Transistor counts reflect this generational gap: the GT 645M has 1,270 million transistors on a 118 mm² die (density of 10.8M / mm²), whereas the Vega 3 has 4,940 million transistors on a 210 mm² die (density of 23.5M / mm²). The Vega 3's transistor density is more than double that of the GT 645M.

Clock speeds also diverge sharply. The GT 645M runs at a base clock of 709 MHz with a boost of 780 MHz, while the Vega 3 has a much lower base of 300 MHz but boosts to 1100 MHz. Memory configurations are entirely different: the GT 645M has 2 GB of dedicated DDR3 memory on a 128-bit bus with 28.80 GB/s bandwidth, whereas the Vega 3 uses system-shared memory with system-dependent bandwidth. The GT 645M has 384 shading units, 32 TMUs, and 16 ROPs, while the Vega 3 has 192 shading units, 12 TMUs, and only 4 ROPs. Pixel and texture rates follow: the GT 645M achieves 6.240 GPixel/s and 24.96 GTexel/s, while the Vega 3 achieves 4.400 GPixel/s and 13.20 GTexel/s. The GT 645M's FP32 throughput is 599.0 GFLOPS versus the Vega 3's 422.4 GFLOPS, but the Vega 3 adds 844.8 GFLOPS FP16 (2:1) which the GT 645M does not offer. Power consumption differs as well: the GT 645M is rated at 32 W TDP, the Vega 3 at 15 W TDP. Both are integrated graphics (IGP) with no power connectors and portable/motherboard-dependent display outputs. The bus interface differs: PCIe 3.0 x16 for the GT 645M versus IGP for the Vega 3. API support is similar but not identical—both support DirectX 12 and OpenGL 4.6, but the GT 645M lists DirectX 12 (11_0) and Vulkan 1.2.175, while the Vega 3 lists DirectX 12 (12_1) and Vulkan 1.3.

Architecture Differences

The core architectures are from different generations and design schools. The NVIDIA GeForce GT 645M is built on the Kepler architecture, using the GK107 chip, and belongs to the GeForce 600M generation. The AMD Radeon Vega 3 uses the GCN 5.0 architecture, specifically the Picasso chip, and is classified as a Vega IGP (Picasso) generation part. The GT 645M's predecessor was the GeForce 500M, while the Vega 3's predecessor was the GCN 3.0 IGP. Their successors are the GeForce 700M and Vega II IGP, respectively.

The most significant architectural difference is in compute capabilities. The GT 645M has no listed FP16 support, while the Vega 3 provides FP16 at 844.8 GFLOPS with a 2:1 ratio relative to FP32. This indicates the Vega 3's GCN 5.0 architecture is designed for mixed-precision workloads, whereas the Kepler-based GT 645M is strictly FP32-oriented. The Vega 3 also has a higher transistor density (23.5M / mm² vs 10.8M / mm²), reflecting the newer 12 nm process. The shader configuration diverges: the GT 645M packs 384 shading units into 32 TMUs, while the Vega 3 has 192 shading units across 12 TMUs, a ratio that favors the NVIDIA part for texture-heavy work. The Vega 3's very low ROP count (4 vs 16) limits its pixel throughput, which is evident in its 4.400 GPixel/s rate versus the GT 645M's 6.240 GPixel/s. Both support modern APIs, but the Vega 3 has a higher Vulkan version (1.3 vs 1.2.175) and better DirectX feature level (12_1 vs 11_0), suggesting more complete support for recent graphics features.

Where Each One Wins

The NVIDIA GeForce GT 645M wins in scenarios that stress traditional graphics pipelines. Its 16.4% Metal advantage and 23.1% Vulkan advantage make it the better choice for gaming or rendering applications built on those APIs. The higher pixel rate (6.240 GPixel/s) and texture rate (24.96 GTexel/s) support this conclusion, as does the larger ROP count (16 vs 4). The GT 645M also benefits from dedicated 2 GB DDR3 memory, which avoids the bandwidth contention of system-shared memory. Its higher FP32 throughput (599.0 GFLOPS) gives it a raw compute edge for single-precision workloads. Users with older software stacks or those prioritizing Metal/Vulkan compatibility should favor this part.

The AMD Radeon Vega 3 wins decisively in OpenCL compute workloads, with a 32.4% lead that is the largest of any test. This makes it the superior choice for general-purpose GPU computing, physics simulations, or any task that leverages OpenCL. Its FP16 support (844.8 GFLOPS) is a unique advantage for half-precision machine learning or image processing tasks. The Vega 3's lower TDP (15 W vs 32 W) also makes it more power-efficient, which is relevant for battery-powered systems. The higher boost clock (1100 MHz vs 780 MHz) suggests better short-burst performance despite the lower base clock. For users running compute-intensive workloads that can use OpenCL or FP16, the Vega 3 is the clear winner, even though it loses in graphics API benchmarks.