Upon every reboot, I have to try several times before my cards are recognized.  Does anyone else have that?  ie If I cut power (via 'restart' or physically with a switch), upon reboot, attempting to disable gpu's only results in one or two disabling (and conversely one or two are recognized)..  It varies which gpu's won't be recognized, but if they're unrecognized, disabling does not help me, so I attempt rebooting again.  I've changed out risers, but since it's a different gpu giving me problems every time, I'm stumped.  Sometimes I have to wait several minutes w/o power or plug in a physical monitor, but nothing seems to work 100%. 
When running, the rig will go for days at a time w/o a hitch, but if there's any day (like this morning) when I wake to find the power's been cut for a second, the miner will be idling because my script failed at startup.  Any ideas?