I'm running a GS2 and a NF2 on the same powered usb 2 hub with peripherals and memory. Followed advise printed by sidehack and -cv for cgminer. Raspi B kept halting, but I put the temp widget on the screen and added fans. A Vornado clip on, and a 2nd clip on, above, pushing, and a desk fan pulling, and now the temp doesn't go up to the 58 plus range anymore, stays in the low 40s( F ).  Has not locked up for several days.  Note: not USB fans.  I was ready to buy a Vornado desk fan to push, but things seem real stable.