Compute
Once upon a time, the Titan name represented prosumer-level functionality. In addition to great gaming performance, Nvidia’s original Titan boasted theoretical FP64 processing power on par with the company’s Quadro and Tesla cards via GK110. That changed from Maxwell onward, where double-precision fell to 1/32 the rate of peak FP32 performance. Half-precision in the Pascal generation is even worse: you get a 1/64 rate of FP16 compared to FP32.
With each card configured as default, the difference between Titan Xp and the more hobbled GP102-based boards is evident. Those extra CUDA cores play the most prominent role in a compute workload, where they’re front and center. We measure an almost-8% improvement in single-floats and a >11% speed-up versus Titan X in double-floats using Sandra 2017.
The GeForce GTX Titan looks homely at the bottom of our chart. But if you jump into Nvidia’s driver control panel and enable "GeForce GTX Titan" under the Double precision drop-down menu, GPU Boost gets disabled and the FP64 cores operate at 8x their original frequency. Single-float performance takes a big hit, dropping to 2.66 Gpix/s. However, doubles jump from 171.09 Mpix/s to 2 Gpix/s. That’s more than two times the FP64 performance of Titan Xp or GeForce GTX 1080 Ti!
Nvidia’s Maxwell and Kepler architectures don’t support mixed precision like Pascal does, so they’re forced to emulate half-floats at the same rate as FP32 mode. Meanwhile, the GP102-based boards post real-world half-float results around 40% of their double-float numbers.
A 10-minute test run gives FAHBench plenty of time to warm up each card with a sample molecular dynamics calculation. The difference between single- and double-precision compute performance isn’t as pronounced here as it is in Sandra. To that point, Titan Xp’s extra CUDA cores only translate to a 4%-higher score compared to Titan X in a single-precision run.
By far, the biggest revelation comes from Nvidia’s GeForce GTX Titan, which is again humbled at the bottom of our chart. Flipping on its driver-based FP64 switch knocks the single-precision score down to 46.1793, while double-precision jumps to 17.8684. For a second time, we see the four-year-old card outperform Nvidia’s fastest desktop-class board.
A 7% speed-up over Titan X in LuxMark’s OpenCL renderer lands somewhere between our numbers in Sandra and FAHBench. Previous-gen GPUs are significantly slower.
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