> there's something really funky going with the comparison between the desktop and the laptop.
The OP has relatively old GPU in the desktop, GeForce GTX 770 is from 2013, it delivers up to 3.2 TFlops single precision.
The laptop is much newer, its’ from 2016, and the Intel GPU delivers 0.7-0.8 TFlops. The raw computational power is different, but not 10 times different, just 4 times.
The reason why OP has measured 2 times difference not 4 times is probably because data access costs. Intel GPU is integrated so it has very fast access to system RAM. nVidia GPU in the desktop needs to copy data from system RAM to VRAM over the PCIx.
PCIx is slower, both bandwidth (CPU to RAM:
34.1 GB/s, PCIx 3.0: 985 MB/s per lane i.e. 15.76 GB/s for 16x), and especially latency.
The OP has relatively old GPU in the desktop, GeForce GTX 770 is from 2013, it delivers up to 3.2 TFlops single precision.
The laptop is much newer, its’ from 2016, and the Intel GPU delivers 0.7-0.8 TFlops. The raw computational power is different, but not 10 times different, just 4 times.
The reason why OP has measured 2 times difference not 4 times is probably because data access costs. Intel GPU is integrated so it has very fast access to system RAM. nVidia GPU in the desktop needs to copy data from system RAM to VRAM over the PCIx. PCIx is slower, both bandwidth (CPU to RAM: 34.1 GB/s, PCIx 3.0: 985 MB/s per lane i.e. 15.76 GB/s for 16x), and especially latency.