So I've had my AntMiner U2 running at 2 gh/s for around 3 weeks now (since I got it) without any overclocks, which I was very impressed with. I do not have it runing 24/7, but it's more of a hobby than a full-time thing so I just have it running whenever I'm on the computer, which is still 4-6 hours a day. But now, it's going super slow. BFGMiner says it's running a bit under 400mh/s, and in the past 10 hours I've only gotten 3080 accepted shares. The only reason I've left it on all night was because I knew heat wouldn't be a problem, as it's not even heating up to what it used to be getting to. I have tried both using every USB 3.0 ports on my computer and my powered USB hub (plugged into my wall) but still get the same ~400mh/s. I'm super confused, because it's been working forever now and is just now doing this. Plus, BFGMiner no longer recognizes my device as "antminer" anymore. I have to manually go into BFGMiner using M and + and add the device using "erupter:all" or "erupter:\.\COM6". I've tried unplugging it and replugging it in and restarting my machine serveral times. Here's my normal Start.bat file: bfgminer.exe -o http://api.bitcoin.cz:8332 -u XXX -p XXX -S antminer:all --set-device antminer:clock=x0781 and this is the one I must use if I don't want to manually add the "erupter" in: bfgminer.exe -o http://api.bitcoin.cz:8332 -u NoahWL1.worker1 -p 5UD3rghG -S erupter:all --set-device erupter:clock=x0781. An help will be appreciated, thanks!
EDIT: Somewhere else someone suggested using this: bfgminer.exe -o http://api.bitcoin.cz:8332 -u XXX -p XXX -S all --icarus-options 115200:1:1 --icarus-timing 3.0=100 and I got the same results. I then changed it to bfgminer.exe -o http://api.bitcoin.cz:8332 -u XXX -p XXX -S all --icarus-options 115200:2:2 --icarus-timing 3.0=100 and on average got a bit over 700 mh/s, which is better but still nowhere near the 2gh/s I used to be getting.
EDIT: Somewhere else someone suggested using this: bfgminer.exe -o http://api.bitcoin.cz:8332 -u XXX -p XXX -S all --icarus-options 115200:1:1 --icarus-timing 3.0=100 and I got the same results. I then changed it to bfgminer.exe -o http://api.bitcoin.cz:8332 -u XXX -p XXX -S all --icarus-options 115200:2:2 --icarus-timing 3.0=100 and on average got a bit over 700 mh/s, which is better but still nowhere near the 2gh/s I used to be getting.
I don't think that you need the api part in the address, nor do you need icarus related parameters.
Assuming that you are trying to mine on Slush's pool (http://mining.bitcoin.cz/) then you need something like:
bfgminer.exe -o stratum+tcp://stratum.bitcoin.cz:3333 -u User -p Password -S antminer:all --set-device antminer:clock=x0981
The last part is for overclocking the AntMiner U2 to a safe rate of about 2.06 GH/s.
You may want to cool it with a fan. This assumes also that you installed the Silabs driver for the AntMiner (http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx).
Cheers