Can anyone help me out.  I am attempting to build a 6 GPU mining rig but I can only get windows to recognize 5 cards.  So here is my System I am running:

1x Gigabyte 990FX-UD3
6x MSI R280x
8GB PNY Ram
1x Corsair 1050 watt PSU
1x Corsair 850 watt PSU
1x AMD Sempron 145
64GB Hard Drive
Dual Power Supply Adapter
6x Powered Riser Cables

Ok so I will try to explain what's going on and hopefully someone can help me out.  In the beginning I could get windows to recognize all 5 cards, but when I started CGMINER 3.7.3 Kalroth's.  I now have 5 cards hashing away at 695 kh/s with no HW errors and about 0.6% rejected shares.  However, the problem I am having is getting Windows 8.1 to recognize all 6 cards.  I keep getting a code 43 error.  I used Windows update to download all device drivers and I am using the latest Catalyst Drivers I believe.  Does anyone have any suggestions?