So for giggles, I'm going on a hunch, and pulling the single card that's not hashing as well. So now the PSU is only running 9 blades, so if the PSU was slightly overloaded, perhaps this will resolve it. Either way that blade's errors % kept climbing pretty quickly over time. When I first fired up the blade it was around 4.5%, as of now before pulling it the errors were up to 7.6% while the rest are between 0.75 and 1.25%.
Here is the BFGminer output just after pulling that blade:
bfgminer version 3.6.0 - Started: [2013-11-28 00:47:58] - [ 0 days 15:50:59]
[M]anage devices [P]ool management [S]ettings [D]isplay options [H]elp [Q]uit
Connected to stratum-lb-usa48.btcguild.com diff 64 with stratum as user XXXXXXX_Blade
Block: ...82f92e0f #272015 Diff:609M ( 4.36Ph/s) Started: [16:38:46]
ST:3 F:0 NB:120 AS:0 BW:[ 57/ 47 B/s] E:446.44 I: 3.38mBTC/hr BS:626k
9 | 93.38/101.6/98.10Gh/s | A:20410 R:278+128(2.0%) HW:21226/1.6%
--------------------------------------------------------------------------------
PXY 0: | 9.98/10.18/ 9.90Gh/s | A: 2074 R: 30+ 13(2.0%) HW: 992/.73%
PXY 1: | 10.27/10.19/ 9.86Gh/s | A: 2052 R: 22+ 20(2.0%) HW: 1702/1.3%
PXY 2: | 12.39/10.15/ 9.84Gh/s | A: 2049 R: 26+ 13(1.9%) HW: 1517/1.1%
PXY 3: | 9.34/10.20/ 9.91Gh/s | A: 2088 R: 22+ 14(1.7%) HW: 1549/1.1%
PXY 4: | 11.86/10.13/ 9.88Gh/s | A: 2019 R: 31+ 6(1.8%) HW: 903/.67%
PXY 5: | 9.66/10.21/ 9.93Gh/s | A: 2009 R: 25+ 17(2.0%) HW: 988/.73%
PXY 6: | DEAD /10.00/ 9.06Gh/s | A: 1837 R: 25+ 11(1.9%) HW:10084/7.6%
PXY 7: | 9.51/10.20/ 9.86Gh/s | A: 2124 R: 38+ 11(2.3%) HW: 1471/1.1%
PXY 8: | 10.44/10.20/ 9.94Gh/s | A: 2083 R: 28+ 11(1.8%) HW: 977/.72%
PXY 9: | 8.86/10.18/ 9.90Gh/s | A: 2075 R: 31+ 12(2.0%) HW: 1044/.77%