Performance undeniably improved after cleaning the thermal paste. By this I mean the units lasted longer but still Zombie'd. Replacing the USB cables then let me get to where I am at today. It might be worth just changing the USB cables without doing the paste to see if that would have been enough as cleaning the paste is a pain and is not for everyone.
I never got 3 to run together because I sold one before I got the new USB cables.
Now after running for a few days one of the units will Zombie. Unplugging/replugging gets it to work again but only for a short while. Cycling power and USB plug/replug gets it to work for another 4 days or so.
Hope this helps.
I have used my own USB cables since day 1, my first U3 would not run at all with the factory cable. My second U3 I threw the factory USB cable in the trash right away.
Were you able to run two U3s together before you cleaned the thermal paste is I guess what I'm getting at. I haven't applied paste since I build my computer years ago, I know it's a pain, which is why I'm putting it off, but I just may have to try it to say I've tried everything.
Other than that maybe my computers have USB issues, I read through this thread again and noted at least 5 different people who were able to run 2 at once. I wonder why it works for them but not for me.
The other weird thing is that I can run four nanofury usb stick miners at the same time with one U3 just fine, so the conflict is definitely something U3 to U3. I'll clean up the paste anyway, because they'll run cooler with a proper application.