Is a certain amount of hardware error acceptable? What actually happens when there is a hardware error? I'm using CGminer 3.8.2 on a Win 7 PC. All miners are directly connected to a USB port not using a hub. This is what I'm getting, speed don't seem to be that great too. 
That's by design in these chips. An error rate around 10% is to be expected. I can make it read zero artificially in cgminer if you like...
The best unmodified hashrate on these devices you can expect is 2.3GH on some of them. Most are in the 2-2.2GH rate until they're modded.