Yah, I have no clue why the datatable.png isn't showing up any more. I've also seem to have lost the ability to edit this post. The mag at the time of this post was about 25 per Odroid, now it's about 12.

Here's an updated table. Disregard the Z620 and the laptops and the Nano Pi Neo Air. They were shut off for the last 5 weeks because I went on a camping trip, but I did leave the rest powered on (right click, then open in new tab to see this clearly):

The payback periods are being calculated on a mag unit of 0.417. I'm not sure if this is correct, but to create 48k POR coins per day with only 115k total magnitude, I'm assuming this will be the long-term average. Though since March, this has NOT been the case, which I still don't understand. It seems to be between 0.20 and 0.25. So, to summarize, take my payback period numbers with a grain of salt. They could be twice as long as shown, or even worse, these could be completely unprofitable at current GRC prices and current mag units.