I just placed an order for some g4600's. I will see how that works - the rig that had been crashing every couple hours crashed after 24 hours after I turned off teamviewer - hopefully this puts me over the top.
As for power, both are built the same way. Each is running on 2 750w EVGA G3 power supplies. Each SATA/molex power connector is running no more than 2 GPU risers. The molex connectors (and single SATA) hooked to the board each share with the riser for a single GPU (this means 13 GPU's, 2 motherboard molex, and 1 motherboard SATA to connect. The PSU's each have 3 SATA and 1 Perif (molex) connector, hence my using two connections per cable). I did have a 550w PSU in the mix (as a third) to see if that would change things, but it did not.
The only other discernable different is that not all GPU's are the same brand/make (but all are 1060 6GB), and the risers are not all identical (though I have switched them out in troubleshooting).
Good, G4600 is 2 core, 4 threads CPU. That will definetely help, much better than Celerons you have.
As for the mixed GPU's, try to put as many of the same brand/model in the same rig. Then you will have to manualy set overclocking for each GPU. Don't use the global OC for all. Try with the lowest stable value for all (I believe it was about 600 memory for you), then increase +50 memory on one brand/model and see if it's stable, then try +50 on different model and see if it's stable, then repeat until you get max for all models. It will take a while to fine tune it, that's the downside of mixed cards. Good luck and keep us posted.
Yesterday I swapped both Celeron G3930's for G4600's.
Overnight, the stable rig remained stable, the unstable rig crashed again.
Short of replacing all my risers again (and I am still open to specifics on what version to get) or RMA'ing the motherboard, is there anything else I might be missing?
JudoFlash, have you tried my previous suggestion of manualy overclocking each card, not using the global settings since you have a mix of different cards?
If that doesn't work, disconnect one card completely, then run the rig, see if it's stable. If it still crashes, connect the disconnected card back and disconnect another card completely... repeat until you pinpoint the card that misbehave. Once you pinpointed the troublemaker, troubleshoot further: replace the riser, replace the adapter cable to the riser (depends on your risers, PCIe to SATA or Molex to SATA cable), plug the riser power to another connector of the SATA cable coming from the power supply, lastly, significantly lower the overclock values for that card. If previous steps didn't help, you have a bad GPU, replace it.
I've had problems with, bad riser, bad power adapter cable, bad SATA connector and bad GPU before. It's not easy to troubleshoot when the problem is intermittent but atleast with the above suggestion (disconnecting one card at a time completely) you can narrow the problematic section then troubleshoot further.
BTW, I am using version 006-c risers with PCIe to SATA power adapter cables.
Thank you. Yes I have tried the manual tuning. Right now I have everything running at stock as sort of a "last ditch" effort on making this configuration work (or at least narrowing it down). As you said, the challenge is that it does not crash right away (sometimes it takes 24 hours or so), so with so many variables, it takes a long time to pinpoint. I ordered some new risers (I would need them anyway as I plan to set up another rig or two), so I will do some further testing with those once I have them.
I appreciate everyone's input. Yes, I know I could just stand up another board and not have so much riding on this one, but I feel longer term, finding the issue will help my overall success. Plus, folks on this forum seem to be making things work with this board and similar setups.
Also, I'm stubborn.