Just bought a couple of these USB erupter for a very small amount of money (check it on Amazon).
The Antminer U2 are sold for a 2GH/s power mining but I just discovered that, with an adeguate extra cooling system, it’s very simple and efficient to overclock them to 2.4GH/s.
I’m using MinePeon to manage my miners and after overclocking them now I have a 20% more gigahash power without losing a share (no errors at all).
Overclocking it’s simple, just drop and extra param to the bfgminer startup script (but you can use your preferred miner command), something like this:
bfgminer -S all -o <pool-server> -u <pool-user> -p <pool-pass> \ --set-device antminer:clock=0B81
The antminer will reach the 2.4GH/s in fews minutes, but remember to add extra cooling to the erupter because they will be very hot without it and you risk to obtain a lot of errors or bad you could damage the Antminer. (You have been warned!)
I played with some Lego to build a perfect cooling system to keep them cold and it works great, as you can see in the picture I used a old PC fan connected via USB to get power. I don’t suggest to supply power from the main erupters HUB (here a D-Link DUB-H7 you can’t see), if you have enough power get it from the RPi or the PC used to manage the miners.
Some useful links:
- Antminer Official Documents / Datasheets
- Antminer U1 User Guide with every overlocking frequency (I can say that they are the same for U2 version)
(Overclocking your device can damage it and I’m not absolutely responsible of that. Use this guide at your own risk.)