I've written some stuff about that in the other thread you got linked to, but I would like to add something:

A single rack costs $1900/month in Calgary, and has insufficient power (15A) for dense packing.

So a commercial rack already costs more than OpenBSD needs in electricity, but OpenBSD has about 3 racks worth of gear.

So, apparently they are testing on bunch of old and/or strange hardware https://news.ycombinator.com/item?id=7070713

It's been covered before in the many HN threads on this issue. Search is your friend.

They have these "computer" things that actually use electricity just to work. Worst of all, they produce heat, so then they have to use this "air conditioning" machine to make it cool again. Crazy stuff.