NVIDIA GeForce GTX 780M vs NVIDIA Tesla K20c Comparison

The NVIDIA Tesla K20c and NVIDIA GeForce GTX 780M are both Kepler-generation parts from the same manufacturer, but they target entirely different corners of the market. The data shows a clear split between a workstation-oriented compute card and a high-end mobile GPU, with the benchmark results revealing a surprising winner in raw compute performance. This analysis digs into the specifications, architectural differences, and the single head-to-head benchmark to determine which card holds up better under scrutiny.

FAQ

Q: Which GPU has the higher average benchmark score?

A: The NVIDIA GeForce GTX 780M holds a higher average benchmark score of 11,261, while the NVIDIA Tesla K20c trails slightly with an average score of 11,479. The delta between them is 1.9% in favor of the GTX 780M.

Q: How does the Tesla K20c compare to its closest rival, the AMD Radeon Pro 5500M?

A: The Tesla K20c scores 11,479 versus the AMD Radeon Pro 5500M’s 11,528, a difference of -0.4%. This places the Tesla K20c essentially on par with its nearest competitor, with a negligible performance gap.

Q: What is the architecture and process node for both cards?

A: Both GPUs are built on the Kepler architecture using a 28 nm process node fabricated by TSMC. The Tesla K20c uses the GK110 chip, while the GTX 780M uses the GK104 chip.

Q: What is the memory bandwidth difference between the two cards?

A: The Tesla K20c offers 208.0 GB/s of bandwidth across a 320-bit bus, whereas the GTX 780M provides 160.0 GB/s over a 256-bit bus. The Tesla K20c has a 30% bandwidth advantage.

Q: Which card has a higher pixel rate?

A: The Tesla K20c achieves a pixel rate of 36.71 GPixel/s, significantly higher than the GTX 780M’s 25.50 GPixel/s. This indicates the Tesla K20c has a clear edge in fill-rate-bound tasks.

Q: Are both cards still in production?

A: No, both are marked as end-of-life. The Tesla K20c was released on 2012-11-11, and the GTX 780M followed on 2013-05-10.

Architecture Differences

The underlying architecture is where the two diverge most sharply, despite sharing the Kepler name and 28 nm TSMC process. The Tesla K20c is built around the GK110 silicon, a massive die measuring 561 mm² with 7,080 million transistors. In contrast, the GTX 780M uses the GK104 chip, which is significantly smaller at 294 mm² and houses just 3,540 million transistors. This means the Tesla K20c packs nearly double the transistor count into roughly double the die area, yielding a transistor density of 12.6M / mm² versus 12.0M / mm² for the GTX 780M.

The compute resources tell a similar story of scale. The Tesla K20c fields 2,496 shading units, 208 texture mapping units, and 40 ROPs. The GTX 780M has 1,536 shading units, 128 TMUs, and 32 ROPs. That is a 62.5% advantage in shader count and a 62.5% advantage in TMUs for the Tesla K20c, while its ROP lead is a more modest 25%. These numbers suggest the Tesla K20c is designed for throughput-heavy workloads, whereas the GTX 780M is a trimmed-down part for mobile power constraints.

Memory configurations also set them apart. The Tesla K20c has 5 GB of GDDR5 on a 320-bit bus, while the GTX 780M has 4 GB on a 256-bit bus. The Tesla K20c’s memory clock is 1300 MHz (5.2 Gbps effective) versus 1250 MHz (5 Gbps effective) for the GTX 780M, contributing to the bandwidth gap mentioned earlier. Clock speeds for the core differ too: the GTX 780M has explicit base and boost clocks of 771 MHz and 797 MHz, while the Tesla K20c’s base and boost clocks are not listed in the data pack.

The form factor and interface underline their different purposes. The Tesla K20c is a dual-slot PCIe 2.0 x16 card with a 267 mm length and requires a 1x 6-pin plus 1x 8-pin power connector. The GTX 780M is an MXM Module with an MXM-B (3.0) interface, has no dedicated power connectors, and its display outputs are portable-device-dependent. The Tesla K20c has no display outputs at all, marking it as a pure accelerator.

Head-to-Head Benchmarks

The only direct head-to-head benchmark available is Geekbench OpenCL, and the results are counterintuitive. The GTX 780M scores 12,769, while the Tesla K20c scores 11,479. That gives the GTX 780M a 10.1% victory, despite the Tesla K20c’s vastly larger silicon and compute resources. This is a meaningful upset in the data, as the deltaPct of -10.1% (from the Tesla K20c’s perspective) indicates a clear win for the smaller, lower-power mobile part.

Why would this happen? The Tesla K20c’s 3.524 TFLOPS of FP32 performance is substantially higher than the GTX 780M’s 2.448 TFLOPS, yet the OpenCL workload does not reflect that advantage. The GTX 780M’s higher core clocks, with a base of 771 MHz and boost of 797 MHz, might partially compensate, but the Tesla K20c’s clock speeds are unspecified in the pack. It is plausible that the Tesla K20c is running at lower frequencies in this test, or that the OpenCL driver optimizations favor the GTX 780M’s architecture. The data does not provide a definitive explanation, but it suggests that raw spec counts do not always translate to real-world benchmark wins.

The GTX 780M also has additional benchmark results in the pack, scoring 8,319 in Geekbench Metal and 12,696 in Geekbench Vulkan. No corresponding results are listed for the Tesla K20c, so the OpenCL score is the only point of direct comparison. This single data point flips the expected hierarchy, making the GTX 780M the winner in the head-to-head category.

Specification Differences

The two cards differ across nearly every measurable specification, reflecting their divergent design goals. The Tesla K20c uses the GK110 chip, while the GTX 780M uses GK104, and their transistor counts are 7,080 million versus 3,540 million, respectively. Die size follows suit at 561 mm² for the Tesla K20c and 294 mm² for the GTX 780M. Transistor density is slightly higher on the Tesla K20c at 12.6M / mm² versus 12.0M / mm².

Memory specifications diverge in three key areas: capacity is 5 GB for the Tesla K20c versus 4 GB for the GTX 780M; bus width is 320-bit versus 256-bit; and bandwidth is 208.0 GB/s versus 160.0 GB/s. Memory clocks are 1300 MHz (5.2 Gbps effective) for the Tesla K20c and 1250 MHz (5 Gbps effective) for the GTX 780M.

Compute unit counts are consistently higher on the Tesla K20c: 2,496 shading units versus 1,536, 208 TMUs versus 128, and 40 ROPs versus 32. Pixel rate is 36.71 GPixel/s versus 25.50 GPixel/s, and texture rate is 146.8 GTexel/s versus 102.0 GTexel/s. FP32 performance is 3.524 TFLOPS versus 2.448 TFLOPS.

Power and physical characteristics are starkly different. The Tesla K20c has a TDP of 225 W and requires a 550 W suggested PSU, while the GTX 780M has a TDP of 122 W with no suggested PSU listed. The Tesla K20c is dual-slot with a 267 mm length and 1x 6-pin plus 1x 8-pin connectors; the GTX 780M is an MXM Module with no connectors. Bus interface is PCIe 2.0 x16 versus MXM-B (3.0). Display outputs are absent on the Tesla K20c, whereas the GTX 780M’s are portable-device-dependent.

Clocks are another differentiator: the GTX 780M lists base and boost clocks of 771 MHz and 797 MHz, while the Tesla K20c has none specified. Release dates also differ, with the Tesla K20c launching on 2012-11-11 and the GTX 780M on 2013-05-10. The Tesla K20c has a launch MSRP of 3,199 USD, while the GTX 780M has no listed launch MSRP.

Where Each One Wins

The GTX 780M wins the only head-to-head benchmark, taking the Geekbench OpenCL test with a score of 12,769 versus the Tesla K20c’s 11,479. This is a 10.1% margin, and it gives the GTX 780M the sole victory in the wins column. Its additional scores in Metal (8,319) and Vulkan (12,696) suggest broader API coverage in the data, though no Tesla K20c equivalents exist for direct comparison.

The Tesla K20c wins on nearly every raw specification front. It has more memory, wider bus, higher bandwidth, more shading units, more TMUs, more ROPs, and higher pixel and texture rates. Its FP32 throughput of 3.524 TFLOPS is 44% higher than the GTX 780M’s 2.448 TFLOPS. For workloads that scale with raw compute density—such as large matrix operations or high-resolution rendering—the spec sheet points clearly to the Tesla K20c as the more capable part.

The GTX 780M’s advantage lies in efficiency and portability. Its 122 W TDP is nearly half the Tesla K20c’s 225 W, and its MXM form factor makes it suitable for laptops. The Tesla K20c, by contrast, is a dual-slot desktop card with no display outputs, requiring a beefy power supply. The GTX 780M also has a higher average benchmark score (11,261 versus 11,479) and a better percentile rank among all GPUs, sitting at the 50th percentile versus the Tesla K20c’s 51st.

The Verdict

The data presents a nuanced picture. For anyone focused solely on benchmark scores, the GTX 780M is the winner, delivering a 10.1% higher OpenCL score and a 1.9% higher average across its benchmarks. Its lower TDP and mobile form factor make it the practical choice for portable systems, and its direct benchmark victory cannot be ignored.

However, the Tesla K20c’s specifications point to a different kind of strength. With double the transistors, nearly double the die area, 30% more memory bandwidth, and 44% more FP32 throughput, it is built for sustained compute workloads that do not appear in the limited Geekbench OpenCL test. Its 5 GB VRAM and 320-bit bus are better suited for large datasets, and its no-output design indicates a server or workstation role where display is irrelevant.

The verdict depends on context. The GTX 780M is the winner in the head-to-head benchmark and for mobile use cases, offering better measured performance in the available data. The Tesla K20c is the spec-sheet champion, with superior resources that likely shine in compute-intensive applications not captured by the benchmark suite. Users prioritizing raw benchmark numbers should lean toward the GTX 780M, while those needing maximum memory bandwidth and shader throughput for specialized workloads may find the Tesla K20c’s architecture more compelling, despite its higher power draw and lack of display outputs.