NVIDIA GeForce GTX 780 vs NVIDIA Tesla K20m Comparison

The NVIDIA GeForce GTX 780 and NVIDIA Tesla K20m are both built on the same GK110 Kepler chip, yet they serve fundamentally different purposes. The benchmark data shows that the GTX 780 edges out the Tesla K20m in average score, with a 0.4% delta in its favor. Both cards sit at the 64th percentile among all GPUs, placing them in the mid-range of overall performance today. However, the head-to-head benchmark results reveal a more complex picture: the GTX 780 wins both available tests, but the margin is far from uniform.

Head-to-Head Benchmarks

The most decisive victory for the GeForce GTX 780 comes in Geekbench OpenCL, where it scores 22,863 against the Tesla K20m's 16,241. That is a 40.8% lead, a massive gap that dwarfs the overall average score difference. This result indicates that the GTX 780 is substantially stronger in compute workloads that stress raw parallel throughput as measured by OpenCL. The Tesla K20m, despite being marketed as a compute-focused card, falls significantly behind here, likely due to its lower memory bandwidth and reduced pixel and texture fill rates.

In the Geekbench Vulkan test, the GTX 780 again takes the win, scoring 24,514 versus 21,936 for the Tesla K20m. The delta here is 11.8%, which is a more modest advantage but still a clear, consistent victory. Vulkan workloads tend to leverage both graphics and compute paths, and the GTX 780's higher base configuration—more ROPs and a wider memory bus—helps it maintain a lead. Across both tests, the GTX 780 wins 2 out of 2 head-to-head comparisons, while the Tesla K20m secures zero wins.

The average benchmark scores tell a similar but tighter story: the GTX 780 averages 19,164, while the Tesla K20m averages 19,089. The delta of 0.4% means the GTX 780 is effectively 0.4% faster on average, which is within the noise of synthetic benchmarks. Both cards are closely matched in their nearest rivals: the GTX 780 is 0.1% behind the NVIDIA TITAN Xp (19,177) and 0.6% ahead of the GeForce RTX 4050 Mobile (19,049). The Tesla K20m, meanwhile, is 0.2% ahead of the RTX 4050 Mobile and 0.3% ahead of the AMD Radeon RX 6600 (19,036). The data suggests that while the GTX 780 is the faster card overall, the difference is marginal in aggregate, yet the OpenCL gap shows it can be decisive in specific compute scenarios.

Architecture Differences

Both cards share the same fundamental architecture: GK110 silicon on a 28 nm TSMC process, with 7,080 million transistors and a die size of 561 mm². The transistor density is identical at 12.6M per mm². This means the core design philosophy is the same, but the implementation diverges in several key ways.

The GTX 780 is a consumer GeForce 700 series part, while the Tesla K20m belongs to the Tesla Kepler (Kxx) generation aimed at professional compute. The GTX 780 has 2,304 shading units, 192 texture mapping units, and 48 ROPs. The Tesla K20m has more shading units at 2,496 and more TMUs at 208, but fewer ROPs at 40. This is a critical trade-off: the Tesla has more parallel compute cores but less fixed-function pixel processing capability. The GTX 780's clock speeds are explicitly listed with a base of 863 MHz and a boost of 902 MHz, while the Tesla K20m's base and boost clocks are not provided in the data, making direct frequency comparison impossible. The GTX 780's memory runs at 1,502 MHz (6 Gbps effective), while the Tesla K20m's memory runs at 1,300 MHz (5.2 Gbps effective), a 15.5% advantage for the GTX 780 in memory clock.

The GTX 780 features 3 GB of GDDR5 on a 384-bit bus, yielding 288.4 GB/s of bandwidth. The Tesla K20m offers more capacity at 5 GB of GDDR5 but on a narrower 320-bit bus, resulting in 208.0 GB/s of bandwidth. That is a 28% bandwidth deficit for the Tesla, which explains much of the OpenCL performance gap. The GTX 780 also has a higher pixel rate of 43.30 GPixel/s versus 36.71 GPixel/s for the Tesla, and a higher texture rate of 173.2 GTexel/s versus 146.8 GTexel/s. In FP32 compute, the GTX 780 delivers 4.156 TFLOPS, while the Tesla K20m delivers 3.524 TFLOPS, a 17.9% lead for the consumer card. Neither card supports FP16, RT cores, or tensor cores.

The bus interface also differs: the GTX 780 uses PCIe 3.0 x16, while the Tesla K20m uses the older PCIe 2.0 x16. This affects host-to-device transfer speeds, which can matter in compute workloads that stream data. The GTX 780 has display outputs (2x DVI, 1x HDMI 1.4a, 1x DisplayPort 1.2), while the Tesla K20m has none, confirming its role as a compute-only accelerator. Both cards are dual-slot, use the same power connector configuration (1x 6-pin + 1x 8-pin), and share the same 267 mm length, but the Tesla K20m has a lower TDP of 225 W versus 250 W for the GTX 780.

FAQ

Q: Which card is faster in OpenCL compute?

A: The NVIDIA GeForce GTX 780 is decisively faster, scoring 22,863 in Geekbench OpenCL versus 16,241 for the NVIDIA Tesla K20m, a 40.8% advantage.

Q: Do both cards support the same graphics APIs?

A: Yes, both support DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175, making them equally capable in software compatibility terms.

Q: Why does the Tesla K20m have more shading units but lose in benchmarks?

A: The Tesla K20m has 2,496 shading units versus 2,304 for the GTX 780, but its memory bandwidth is 208.0 GB/s versus 288.4 GB/s, and its FP32 throughput is 3.524 TFLOPS versus 4.156 TFLOPS, so raw core count does not translate to higher performance.

Q: Is there a difference in memory capacity?

A: Yes, the Tesla K20m has 5 GB of GDDR5, while the GTX 780 has 3 GB, but the GTX 780's wider 384-bit bus and higher memory clock give it more bandwidth per byte.

Q: Which card has display outputs?

A: Only the GTX 780 has display outputs (2x DVI, 1x HDMI 1.4a, 1x DisplayPort 1.2); the Tesla K20m has no outputs, so it cannot drive a monitor.

Q: What is the average benchmark score for each card?

A: The GTX 780 averages 19,164, and the Tesla K20m averages 19,089, making the GTX 780 0.4% faster on average.

Specification Differences

The two cards differ across several specification fields, and these differences directly explain their benchmark behavior.

• Memory Size: GTX 780 has 3 GB, Tesla K20m has 5 GB.
• Memory Bus Width: GTX 780 has 384 bit, Tesla K20m has 320 bit.
• Memory Bandwidth: GTX 780 has 288.4 GB/s, Tesla K20m has 208.0 GB/s.
• Memory Clock: GTX 780 runs at 1502 MHz (6 Gbps effective), Tesla K20m runs at 1300 MHz (5.2 Gbps effective).
• Shading Units: GTX 780 has 2304, Tesla K20m has 2496.
• TMUs: GTX 780 has 192, Tesla K20m has 208.
• ROPs: GTX 780 has 48, Tesla K20m has 40.
• Pixel Rate: GTX 780 has 43.30 GPixel/s, Tesla K20m has 36.71 GPixel/s.
• Texture Rate: GTX 780 has 173.2 GTexel/s, Tesla K20m has 146.8 GTexel/s.
• FP32 Performance: GTX 780 has 4.156 TFLOPS, Tesla K20m has 3.524 TFLOPS.
• Base Clock: GTX 780 has 863 MHz, Tesla K20m has no listed base clock.
• Boost Clock: GTX 780 has 902 MHz, Tesla K20m has no listed boost clock.
• TDP: GTX 780 has 250 W, Tesla K20m has 225 W.
• Suggested PSU: GTX 780 recommends 600 W, Tesla K20m recommends 550 W.
• Bus Interface: GTX 780 uses PCIe 3.0 x16, Tesla K20m uses PCIe 2.0 x16.
• Display Outputs: GTX 780 has 2x DVI, 1x HDMI 1.4a, 1x DisplayPort 1.2; Tesla K20m has no outputs.
• Generation: GTX 780 is GeForce 700, Tesla K20m is Tesla Kepler (Kxx).
• Release Date: GTX 780 launched later, on 2013-05-22, versus 2013-01-04 for Tesla K20m.
• Predecessor/Successor: GTX 780 succeeded GeForce 600 and was replaced by GeForce 900; Tesla K20m succeeded Tesla Fermi and was replaced by Tesla Maxwell.

Where Each One Wins

The GTX 780 wins in every benchmark category where data is available, but the nature of those wins dictates different use cases. The 40.8% OpenCL advantage makes the GTX 780 the clear choice for compute tasks that run under OpenCL, such as certain scientific simulations, video encoding, or machine learning inference workloads that rely on that API. Its higher FP32 throughput (4.156 TFLOPS) and memory bandwidth (288.4 GB/s) give it a strong edge for general-purpose compute that is not bound by VRAM capacity. Additionally, the GTX 780's display outputs mean it can serve as a gaming card or workstation GPU for a desktop system, handling both graphics rendering and compute acceleration.

The Tesla K20m's strengths lie in its larger 5 GB memory pool and lower TDP of 225 W. For workloads that need to hold larger datasets on the GPU without spilling to host memory, the extra 2 GB of VRAM is a tangible benefit. The Tesla K20m also runs cooler per the TDP rating, which may be relevant in dense server environments where power budgets are strict. Its 2,496 shading units and 208 TMUs are higher, which could theoretically help in compute kernels that are latency-bound rather than bandwidth-bound, but the benchmark data does not reflect this advantage in practice. The Tesla K20m's lack of display outputs makes it unsuitable for any interactive graphics work, but it is designed for headless compute nodes.

The Verdict

The data is unambiguous: the NVIDIA GeForce GTX 780 is the faster card by every measured benchmark. It wins both head-to-head tests, holds a 0.4% average score advantage, and delivers higher pixel, texture, and FP32 rates. If you need a card that can do both graphics and compute, the GTX 780 is the only option of the two, given the Tesla K20m has no display outputs. For OpenCL-heavy workloads, the GTX 780's 40.8% lead makes it the superior choice, and its higher memory bandwidth and clock speeds back that up.

The Tesla K20m should be selected only when its 5 GB VRAM capacity is a hard requirement and the workload cannot fit within 3 GB. In such cases, the 28% bandwidth deficit and 17.9% FP32 shortfall may be acceptable trade-offs for the extra memory. The Tesla K20m also draws 25 W less power and recommends a 550 W PSU versus 600 W, which can simplify power delivery in constrained systems. However, for any scenario where performance is the priority and memory fits within 3 GB, the GTX 780 is the better pick. The launch MSRP for the GTX 780 was 649 USD, while the Tesla K20m launched at 3,199 USD, but price is not a factor in performance. Both cards are end-of-life, so the decision hinges on specific workload needs: GTX 780 for speed and flexibility, Tesla K20m for capacity and lower power draw.