I figured out what was wrong with the 6th chip :-)

bfgminer version 3.99.0 - Started: [2014-04-05 02:07:05] - [  0 days 00:09:16]
Manage devices Pool management Settings Display options
Connected to stratum.mining.eligius.st diff 16 with stratum as user
Block: ...484af8b3 #294330  Diff:5.01G (35.84Ph/s)  Started: [02:14:47]
ST:8  F:0  NB:3  AS:0  BW:[203/ 27 B/s]  E:20.23  I:40.96uBTC/hr  BS:1.72k
1/6           |  9.72/ 9.55/10.65Gh/s | A:75 R:2+0(2.6%) HW:43/3.0%
-----------------------------------------------------------------------------------------
NFY 0a:       |  1.64/ 1.66/ 1.77Gh/s | A:17 R:1+0(5.6%) HW: 6/2.4%
NFY 0b:       |  1.64/ 1.65/ 1.91Gh/s | A:12 R:0+0(none) HW:14/4.7%
NFY 0c:       |  1.53/ 1.54/ 1.59Gh/s | A:10 R:1+0(9.1%) HW:15/6.4%
NFY 0d:       |  1.57/ 1.61/ 1.66Gh/s | A:11 R:0+0(none) HW: 4/1.9%
NFY 0e:       |  1.64/ 1.66/ 1.83Gh/s | A:12 R:0+0(none) HW: 5/2.1%
NFY 0f:       |  1.68/ 1.70/ 1.83Gh/s | A:15 R:0+0(none) HW: 0/none
-----------------------------------------------------------------------------------------
[2014-04-05 02:12:52] Accepted 0c1ee27c NFY 0c Diff 21/16
[2014-04-05 02:12:52] Accepted 099ab634 NFY 0d Diff 26/16
[2014-04-05 02:12:52] Accepted 0c06c938 NFY 0d Diff 21/16
[2014-04-05 02:12:52] Accepted 0d599353 NFY 0e Diff 19/16
[2014-04-05 02:12:54] Accepted 0ce9c358 NFY 0e Diff 19/16
[2014-04-05 02:12:57] Accepted 0826a4eb NFY 0b Diff 31/16
[2014-04-05 02:13:05] Accepted 047c994e NFY 0a Diff 57/16
[2014-04-05 02:13:06] Stratum from pool 0 requested work update
[2014-04-05 02:13:10] Accepted 0dae182d NFY 0e Diff 18/16

I'll have to try with a different hub tomorrow as this one is quite crappy (at 1.15A dropping down to 3.9V).