Regarding the non-hashing or zombie units - Still using cgminer 3.7.0, I have clocked them back to 300 mhz per unit and still there would be 1-2 non hashing units that would creep up after a few minutes from initialization. The units that stop hashing are physically random (eg: first run unit 9 and 11 would stop; or second run unit 2 and 8 would stop and so forth).
edit:
I've noticed that the unit goes bad due to a usb write error. Don't know if anything came across this usb issue?
Perhaps if there is someone who is running these units with no issues, are you using a usb hub? I'm thinking the hub might be the culprit. Using Dlink 7 port usb 2.0 hub > 5 units per hub.
I use this hub:
Tek Republic TUH-2700 USB 2.0 7 Port Hub with Power
http://www.newegg.com/Product/Product.aspx?Item=N82E16817659004I have one unit that did go zombie or just showed mhs instead of gh,just moved it around to another USB port & another 6pin cable.It hasn't acted up since.
Those same cables are on another miner & it works fine.................No rhyme or reason here,all my power & USB cables are the same,very strange...................
I have a Belkin 7 port USB 2.0 Hub with 7 miners on it.
I tried my Anker 3.0 hubs and they just do not work at all.
Yes, there seems to be no rhYme or reason to the USB errors. I get a Libusb error after a while when I power-cycle and unplug the miners that do not seem to be hashing. Usually after Libusb hits miner 57 or more.
As I unplug them, and plug them in again, to try to get them to hash, the KLN number keeps climbing. Eventually, I get a USB error, and I have to reboot the mining computer. It seems you get these errors on Linux too.
There is some sort of USB limitation. Might depend on the motherboard (no idea here). But, I'm only running 10 miners on the Unix machine. I have not tried additional usb hubs on it, because frankly, it's a HUGE pain in the behind to power cycle them to make them all work. But, such is the price of...err...BTC.
Not all of mine are hashing at full power, all of the time. It is highly annoying. But, right now I'm running on 8 out of 10 on full power, and 2 seem to be running half bank.
Well, at least they are running. Knock on wood.