Board came in today and I'm taking a look at it. New plugs are on order (as I said I like using nickel plugs instead of brass) but in the meantime I thought it would be neat to post some pictures. I'll ultimately add this to a new thread on R4 repair* but unless people don't want me to I'll also post a few pics here.

The board itself:

https://i.imgur.com/tHh64Tj.jpg

R4 boards are interesting. 64 chips, a choke, and the pic circuitry. Nothing complex, but a very long board so the air can roll across it without all the resistance of a normal S9 board. You can also see some of the heat sinks are slightly mis-aligned, but worse things have happened....

https://i.imgur.com/HSsSJOl.jpg

Close up of the end of the board: All three plugs are badly burned. Also oddly enough it's the bottom pins that melt first, which is *very* bad. That's the ground pin, and if all of them open the board will suddenly have +12 and no ground. At which point the electricity will seek a ground and will find it in the signal cable. Which will then burn open, damaging the board's circuitry and possibly the controller. Yuck. You can also run into the situation where the ground vias are burned to the point that there is no conductivity, in which case one has to build a new ground plane. Do-able but a real pain in the rear.

https://i.imgur.com/JKr2Yr7.jpg

Top view, close up where you can see the heat damage to the circuitry on the end. This pin set was really getting hot, the bubbled plastic tells how warm everything got. Check your plugs: If they feel warm then they are too hot and you need to either slow down your miner or get a better power supply.

I'll pull the old plugs this weekend. OP did this board still hash or did it shut down? What's the other board look like, and were they all on the same power supply?