Hi.

Three have been working fine for a few weeks now.  

# 1.6GH/s       0781 (DEFAULT)
# 1.8GH/s       0881 (GOOD)
# 2.0GH/s       0981 (FINE) <1% HW errors (I use this with fan)
# 2.2GH/s       0A81 (UNSTABLE) >5% HW errors

Sample of bfgminer on Linaro Cubietruck and hash rate looks as expected:
ST:6  F:1  NB:748  AS:0  BW:[ 19/  9 B/s]  E:96.68  I: 0.00 BTC/hr  BS:127k
 3            |  6.30/ 6.19/ 5.85Gh/s | A:4382 R:104+1(2.9%) HW:2/.00%
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 AMU 0:       |  2.06/ 2.06/ 1.96Gh/s | A:1447 R: 26+1(2.1%) HW:1/.00%
 AMU 1:       |  2.06/ 2.06/ 1.95Gh/s | A:1442 R: 37+0(3.1%) HW:1/.00%
 AMU 2:       |  2.06/ 2.06/ 1.94Gh/s | A:1493 R: 41+0(3.3%) HW:0/none