I recently setup 2 U3 v2's and I have them running on my mac osx. I am using bfgminer, for some reason I can't get cgminer to work, and both u3's are going no faster than 5 gh/s, top speed i've seen has been 10 gh/s each. Whats the best way to overclock them on a mac?

Hi,
I'm fairly new to mining, I've been using 2 antminer s5 miners which have been working great but my 2 new U3 version 2's don't seem to be working correctly. I'm currently using bfgminer 5.1 for mac. it shows cpu 0 and cpu 1, so at least the two u3's are found but for speeds i'm getting an average speed of .58Mh/s total?!  don't U3's start around 30-60gh/s each?

OCL 0: off
CPU 0: 581.0/493.7/287.3kh/s
CPU 1: 581.0/493.7/287.3kh/s

also messages of
error -54: Enqueueing kernel onto command queue.
OCL 0 Failure, disabling!
attempting to reinitialize OCL 0

-- but it still connects to the pool