NVIDIA Tesla C2075 vs NVIDIA Tesla K20c Comparison

FAQ

Q: Which GPU wins in raw compute performance?

A: The NVIDIA Tesla K20c wins the only head-to-head benchmark. In Geekbench OpenCL, the K20c scores 11,479, while the Tesla C2075 scores 10,400, giving the K20c a 10.4% advantage.

Q: How do these cards compare to their nearest rivals in the database?

A: The K20c sits at the 51st percentile of all GPUs, with its closest rival being the AMD Radeon Pro 5500M (11,528 score, -0.4% delta). The C2075 sits at the 48th percentile, with its closest rival being the AMD Radeon RX 6500M (10,362 score, 0.4% delta).

Q: Which card has more memory and a wider memory bus?

A: The Tesla C2075 has more memory at 6 GB and a wider 384-bit bus, but the Tesla K20c has higher memory bandwidth at 208.0 GB/s compared to 150.3 GB/s for the C2075.

Q: What are the process node and transistor counts for each?

A: The K20c uses a 28 nm process with 7,080 million transistors, while the C2075 uses a larger 40 nm process with 3,000 million transistors. The K20c’s transistor density is 12.6M / mm² versus 5.8M / mm² for the C2075.

Q: Is there a difference in display outputs?

A: Yes. The Tesla C2075 includes a single DVI output, while the Tesla K20c has no display outputs at all, making it a compute-only accelerator.

Q: What is the memory clock speed difference?

A: The K20c runs its GDDR5 memory at 1300 MHz (5.2 Gbps effective), significantly faster than the C2075’s 783 MHz (3.1 Gbps effective).

Architecture Differences

The architectural gap between these two Tesla cards is defined by their respective generations. The Tesla K20c is built on the Kepler architecture with the GK110 chip, while the Tesla C2075 uses the older Fermi 2.0 architecture with the GF110 chip. This generational shift brings substantial changes to the compute core layout.

The K20c packs 2,496 shading units, 208 texture mapping units (TMUs), and 40 raster operation units (ROPs). In contrast, the C2075 offers only 448 shading units, 56 TMUs, and 48 ROPs. While the C2075 has more ROPs, the K20c’s massive lead in shader count and TMUs drives its compute superiority.

The manufacturing process differs as well. The K20c is fabbed on a 28 nm process at TSMC, whereas the C2075 uses a 40 nm process, also at TSMC. This allows the K20c to fit 7,080 million transistors onto a 561 mm² die, compared to the C2075’s 3,000 million transistors on a 520 mm² die. The resulting transistor density is more than double for the K20c (12.6M / mm² vs 5.8M / mm²).

Memory architecture also differs. The K20c has 5 GB of GDDR5 on a 320-bit bus, while the C2075 has 6 GB of GDDR5 on a 384-bit bus. Despite the smaller bus and capacity, the K20c achieves higher bandwidth (208.0 GB/s vs 150.3 GB/s) due to its faster memory clock. The K20c also supports Vulkan 1.2.175, while the C2075 has no Vulkan support listed; both support DirectX 12 (11_0) and OpenGL 4.6.

The Verdict

The data clearly favors the NVIDIA Tesla K20c for any compute-focused workload. It wins the only available head-to-head benchmark by 10.4%, placing it at the 51st percentile versus the C2075’s 48th percentile. The K20c’s Kepler architecture delivers significantly higher shader counts, texture rates, and pixel rates, making it the stronger choice for general-purpose GPU computing.

The Tesla C2075, however, is not without merit. It offers more memory (6 GB vs 5 GB) and a wider memory bus (384-bit vs 320-bit), which could benefit workloads that are capacity-bound rather than bandwidth-bound. It also has a display output (1x DVI), which the K20c lacks, making it the only option of the two for tasks requiring a direct video connection.

For users prioritizing raw compute throughput, the K20c is the definitive pick. Its 10.4% benchmark lead is backed by architectural advantages: 2,496 shading units versus 448, and a texture rate of 146.8 GTexel/s versus 32.14 GTexel/s. The C2075 is a legacy option that should only be considered if memory capacity is the primary constraint, as its 6 GB frame buffer exceeds the K20c’s 5 GB.

Specification Differences

The two cards differ across nearly every core specification, reflecting their generational gap. The K20c’s shading units (2,496) dwarf the C2075’s (448), as do its TMUs (208 vs 56) and texture rate (146.8 GTexel/s vs 32.14 GTexel/s). The pixel rate follows suit: 36.71 GPixel/s for the K20c versus 16.07 GPixel/s for the C2075.

Memory specifications diverge in both capacity and speed. The K20c offers 5 GB of GDDR5 on a 320-bit bus, while the C2075 offers 6 GB on a 384-bit bus. The K20c’s memory clock is higher at 1300 MHz (5.2 Gbps effective) compared to 783 MHz (3.1 Gbps effective), resulting in bandwidth of 208.0 GB/s versus 150.3 GB/s.

The process node is a key differentiator: 28 nm for the K20c versus 40 nm for the C2075. Transistor counts are 7,080 million versus 3,000 million, and die sizes are 561 mm² versus 520 mm². Power consumption differs as well, with the K20c rated at 225 W TDP and the C2075 at 247 W TDP, despite the K20c’s higher performance.

Physical dimensions and outputs also differ. The K20c is longer at 267 mm (10.5 inches) versus 248 mm (9.8 inches) for the C2075. The C2075 has a single DVI output, while the K20c has no display outputs. Both use dual-slot cooling, require 1x 6-pin + 1x 8-pin power connectors, and recommend a 550 W PSU. The bus interface is PCIe 2.0 x16 for both.

Head-to-Head Benchmarks

The sole head-to-head benchmark is Geekbench OpenCL, where the NVIDIA Tesla K20c posts a score of 11,479 against the Tesla C2075’s 10,400. This yields a 10.4% delta in favor of the K20c. This single result encapsulates the performance gap between the two architectures.

Looking at nearest rivals provides additional context. The K20c’s closest competitor is the AMD Radeon Pro 5500M with an average score of 11,528, which beats the K20c by just 0.4%. The K20c also trails the AMD Radeon RX 7800 XT (11,627, -1.3%) and the NVIDIA GeForce GTX 1660 (11,680, -1.7%), while leading the NVIDIA GeForce GTX 780M (11,261, 1.9%).

The C2075’s nearest rival landscape is different. It sits just ahead of the AMD Radeon RX 6500M (10,362, 0.4%) and behind the AMD Radeon RX 550X (10,481, -0.8%). It also leads the NVIDIA GeForce GTX 950A (10,273, 1.2%) but trails the AMD Radeon R9 M275X (10,582, -1.7%).

The 10.4% head-to-head delta is consistent with the percentile gap (51st vs 48th). The K20c’s advantage in shading units (2,496 vs 448) and texture rate (146.8 GTexel/s vs 32.14 GTexel/s) directly translates into the OpenCL score difference, reinforcing that the K20c is the superior compute performer.

Where Each One Wins

NVIDIA Tesla K20c:

• Compute throughput: Wins the only benchmark (Geekbench OpenCL) by 10.4%, with higher FP32 performance (3.524 TFLOPS vs 1,027.7 GFLOPS).
• Texture and pixel processing: Offers 146.8 GTexel/s and 36.71 GPixel/s, far exceeding the C2075’s 32.14 GTexel/s and 16.07 GPixel/s.
• Bandwidth efficiency: Despite a narrower 320-bit bus, the K20c achieves 208.0 GB/s bandwidth versus 150.3 GB/s, making it better for bandwidth-sensitive tasks.
• Modern API support: Adds Vulkan 1.2.175 support, which the C2075 lacks.

NVIDIA Tesla C2075:

• Memory capacity: Provides 6 GB of GDDR5 versus 5 GB on the K20c, a 1 GB advantage for workloads that require larger working sets.
• Memory bus width: The 384-bit bus is wider than the K20c’s 320-bit, which could be beneficial for certain access patterns.
• Display output: Includes 1x DVI, making it the only card of the two that can drive a display directly.
• Lower TDP relative to performance: While its TDP is higher in absolute terms (247 W vs 225 W), the C2075’s older architecture may be sufficient for legacy compute tasks that do not need the K20c’s full throughput.

In summary, the K20c wins decisively on compute performance, bandwidth, and modern API support. The C2075 retains a niche for memory-capacity-bound workloads and any scenario requiring a display output. For all other compute purposes, the data points to the K20c as the stronger accelerator.