What will perform better for raw calculations? 20 orange pi

Probably an i7 6700.

>>55298598
That's what I was thinking too, but I was still curious because it was 20 of the PIs which should still be decent for raw performance.

Would a small cluster of 2 or 3 PIs be enough to host a website on?

>>55298616
>https://en.wikipedia.org/wiki/Raspberry_Pi
>A cluster of 64 Raspberry Pi Model-B computers, labeled "Iridis-pi", achieved a LINPACK HPL suite result of 1.14 GFLOPS (n=10240) at 216 watts for c. 4 000 US$

>https://www.pugetsystems.com/labs/hpc/Intel-Skylake-6700K-with-Parallel-Studio-XE-2016-vs-2015-on-Fedora-23-Much-Better-711/
>The Skylake 6700K @ 4GHz only gave 200 GFLOP/s

As for your question about the website, it would definitely work for a simple site with little users; I imagine you'll start getting difficulties after you start getting 50-100 users a second.

>>55298702
The orange pi boards OP is talking about are much newer and faster than the original raspberry pi in the cluster you quoted. But looking at NEON Linpack results for similar Cortex A7 devices OP would still be looking at only ~18 GLOP/s with 20 nodes absolute best case scenario.