NVIDIA Tesla K40m vs NVIDIA Tesla K80 Comparison

The NVIDIA Tesla K40m and Tesla K80 are both end-of-life dual-slot Kepler compute cards with no display outputs, but they target different needs. The K40m is the faster single-GPU option in OpenCL workloads, while the K80 offers a slightly broader feature set with Vulkan support. The K40m wins the only head-to-head benchmark, but the K80's additional API compatibility makes it a more flexible choice for diverse compute stacks.

The Verdict

The data points to a clear split: the Tesla K40m is the pick for raw OpenCL number-crunching, while the Tesla K80 is better for environments that need Vulkan support alongside OpenCL. In the sole head-to-head benchmark, Geekbench OpenCL, the K40m scores 19,885 against the K80's 18,620, a 6.8% lead. That is a decisive margin for a single benchmark, and it aligns with the K40m's higher clock speeds and greater core counts.

However, the K80 is not without merit. It posts a Geekbench Vulkan score of 19,111, a capability the K40m simply lacks. For builders running modern compute frameworks that lean on Vulkan, this is a functional advantage that no raw OpenCL score can offset. The K80's average benchmark score of 18,866 across two tests also places it in the 63rd percentile of all GPUs, just two points behind the K40m's 65th percentile.

Pick the K40m if your workload is purely OpenCL-based and you want maximum throughput per card. Pick the K80 if you need Vulkan compute or if your software stack is API-agnostic and you want the newer release. The K80 launched later, in November 2014, versus the K40m's November 2013, so it benefits from a more recent design iteration.

Architecture Differences

Both cards are built on TSMC's 28 nm process and share the same 561 mm² die size, but the silicon inside differs. The K40m uses the GK110B chip with 7,080 million transistors, while the K80 employs the GK210 with 7,100 million transistors. Transistor density is nearly identical—12.6M per mm² for the K40m and 12.7M per mm² for the K80—so the extra transistors go toward architectural tweaks rather than density improvements.

The K40m is classified under the original Kepler architecture, while the K80 is labeled "Kepler 2.0." This generation shift shows in the core configuration: the K40m has 2,880 shading units and 240 texture mapping units, whereas the K80 drops to 2,496 shading units and 208 TMUs. Both cards retain 48 ROPs, but the K40m's higher unit counts translate to better fill rates. Pixel rate is 52.56 GPixel/s on the K40m versus 42.85 GPixel/s on the K80, and texture rate is 210.2 GTexel/s versus 171.4 GTexel/s.

Memory architecture is identical in capacity and bus width—12 GB of GDDR5 on a 384-bit bus—but the K40m runs its memory at 1,502 MHz (6 Gbps effective) versus the K80's 1,253 MHz (5 Gbps effective). This yields 288.4 GB/s of bandwidth for the K40m against 240.6 GB/s for the K80. Neither card has RT or tensor cores, and both support DirectX 12 (11_1), OpenGL 4.6, and Vulkan 1.2.175 in their API lists, though the K80's benchmark suite confirms actual Vulkan execution.

FAQ

Q: Which card is faster in OpenCL?

A: The Tesla K40m is 6.8% faster in Geekbench OpenCL, scoring 19,885 versus the K80's 18,620.

Q: Does the Tesla K80 support Vulkan?

A: Yes, the K80 has a Geekbench Vulkan score of 19,111. The K40m has no Vulkan benchmark listed, indicating a lack of practical Vulkan support.

Q: What is the memory bandwidth difference?

A: The K40m has 288.4 GB/s, which is 47.8 GB/s higher than the K80's 240.6 GB/s.

Q: Are these cards the same physical size?

A: Yes, both measure 267 mm (10.5 inches) in length and are dual-slot designs.

Q: Why does the K80 have a lower average benchmark score?

A: The K80's average of 18,866 includes its Vulkan score of 19,111 and OpenCL score of 18,620, dragging the average below the K40m's single OpenCL score of 19,885.

Q: Which card has a higher power draw?

A: The K80 has a 300 W TDP, while the K40m is rated at 245 W. The K80 also requires a higher suggested PSU of 700 W versus 550 W.

Specification Differences

The K40m and K80 diverge on nearly every compute-relevant specification except memory capacity, bus width, and ROP count. The K40m runs a 745 MHz base clock with an 876 MHz boost, while the K80 operates at 562 MHz base and 824 MHz boost. That is a 183 MHz base clock advantage and a 52 MHz boost advantage for the K40m.

Shading units favor the K40m at 2,880 versus 2,496, and TMUs favor it at 240 versus 208. The FP32 throughput is 5.046 TFLOPS for the K40m against 4.113 TFLOPS for the K80, a 0.933 TFLOPS gap. The K80's 300 W TDP is 55 W higher than the K40m's 245 W, and the K80 lists a 1x 8-pin power connector while the K40m's connector type is unspecified.

Memory speed is another clear divider: 6 Gbps effective on the K40m versus 5 Gbps on the K80, producing 288.4 GB/s versus 240.6 GB/s. The K80's transistor count is 20 million higher, but its core clocks are lower, suggesting the GK210 is tuned for different characteristics. Both cards share the same 12 GB GDDR5 capacity, 384-bit bus, PCIe 3.0 x16 interface, and absence of display outputs.

Head-to-Head Benchmarks

The only direct comparison available is Geekbench OpenCL, and it is a decisive win for the K40m. The K40m scores 19,885, while the K80 manages 18,620. The 6.8% delta is substantial in compute terms, reflecting the K40m's higher boost clock and additional 384 shading units. The K80's lower core count and slower memory clock simply cannot overcome this deficit in an OpenCL context.

The K40m's nearest rival data puts its score in perspective. The AMD FirePro W7000 scores 19,905, just 0.1% higher, while the AMD Radeon RX 6650 XT scores 19,765, 0.6% lower. The K40m sits in a tight cluster, meaning its OpenCL performance is competitive with modern mid-range cards, not just its contemporaries. The K80's OpenCL score of 18,620 places it near the NVIDIA GeForce RTX 2070 (18,789, 0.4% higher) and the NVIDIA RTX 2000 Ada Generation (18,954, 0.5% lower). This shows the K80 trails the K40m by a meaningful margin but remains within striking distance of much newer consumer GPUs.

The K80's Vulkan score of 19,111 is its own highlight. It is higher than its OpenCL score, suggesting the GK210's architecture handles Vulkan compute efficiently. The absence of a Vulkan benchmark for the K40m means this is an unqualified advantage for the K80, even though the K40m wins the only shared test.

Where Each One Wins

The K40m wins in raw compute throughput. Its 5.046 TFLOPS FP32 performance, 288.4 GB/s memory bandwidth, and higher fill rates make it the superior choice for OpenCL-heavy workloads like simulation, finite element analysis, or any CUDA-based task that relies on pure shader throughput. The 6.8% OpenCL lead over the K80 is backed by a 0.933 TFLOPS FP32 advantage and a 47.8 GB/s bandwidth advantage. If your application is single-API and that API is OpenCL, the K40m is the logical pick.

The K80 wins on flexibility and feature coverage. Its Vulkan score of 19,111 opens the door to modern compute frameworks that the K40m cannot access. The K80 also benefits from a later release date (November 2014 versus November 2013), meaning longer driver support in practice. For heterogeneous environments where different applications use different APIs, the K80's dual-API support is a practical advantage that benchmarks alone do not capture. The K80's lower core clocks are offset by its higher transistor count, suggesting the GK210 was designed for efficiency in sustained compute rather than peak burst performance.

The K40m is also the lower-power option at 245 W versus 300 W, which matters in multi-GPU racks where thermal density is a constraint. The K80's 700 W suggested PSU versus the K40m's 550 W further reinforces that the K80 demands more from the host system. For builders with limited power budgets, the K40m is the more manageable card. For those needing Vulkan, the K80's extra power draw is the price of entry.