Two out of them is harder to get them start mining, at the very first beginning. and it become harder and harder with each reboot. These two eventually cease to operate yesterday, until now (but still viewable in cgminer console)
I got 2 boards that won't boot up (2nd led keep blinking) but once I turn on the AC to cool the room they boot up in about 1 minute. After that they will hash just fine even with AC off.