I'm running 3 BE's and AntMiner U1 - total ~3GH,
I have the cheapest i5 cpu - it's running on 80-100%,
Is this normal for such low hashing power?
Not sure, but for comparison's sake I have an i5 at 4ghz and am hashing with a BFL Jally at 6.4gh/s. My cpu usage is between 15% and 40%.
On another machine I have 3BE's and a Phenom x4 925 running at 3.2ghz and my cpu usage there is about 15% to 30%.
Hope that helps.