Try changing the voltage/speed of the others? I have some KNC gear that would act like that and required I actually raise the speed of the bum ones above stock, and in some cases lowering voltage. I've also noticed sometimes neighboring DC's if running too high, would shut down the bum ones. Almost seemed as if they were pulling current away from them.
Thanks for the tips, I'll try that. Can't raise clocks above stock, though. 300MHz is the highest selectable speed.
I found a config file in the Titan SD image that had a preconfigured max speed of 475Mhz for the Titan. To overclock the Titan edit waas.c, recompile and install.
Edit: /home/pi/knc-asic/waas/waas.c
Change this line from 300 to 475:
#define MAX_DIE_FREQ_TITAN 475
Then:
cd /home/pi/knc-asic/
make raspberry
cp waas/waas /usr/bin/
Next time you restart bfgminer the advanced page will have selectable speeds up to 475 mhz.
FYI: I had a titan cube overclocked to 400Mhz and was getting about 100Mh/s but the hashrate slipped down quickly over time (even though dcdc's were fine). Not sure why, temps were decentsand everything was working fine.
Might try again at some point.
Note if you are overlocking you had better have damn good connections at the PSU and the Titan. The one I was overclocking was soldered directly to the Titan cube using TWO high quality 6x PCI-E connections (NOT the cheap square pins with the split down the middle).