Have you tried manually selecting the driver for the erroring card? ie: right click, select driver, etc?

Also try disabling and then enabling the card a couple of times. Sometimes that jolts them into working (on older ASrock boards anyway)...

If you've installed the drivers several times you might need to ddu them and start again.

Holy crap guys...I made progress.  Thanks to the link provided by smoolae, I have 5 cards working.  Only 1 card has the yellow bang now!

Here's a copy/paste of the post from the other post:
https://bitcointalk.org/index.php?topic=2401059.new#new

make new key "HackFlags" as (DWORD 32) set value 0x600 as (Hex) in
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\PnP\Pci\
and reboot.

User q43a0ef061ej provided this information.  Maybe if I fiddle with things a bit more I can get all 6 cards working!?

Hey guys, I figured mine out.  In Device Manager, I selected "View" > "Devices by connection".  The 1 card with a yellow bang was then listed next to an audio device.  I disabled the audio device and IMMEDIATELY the 6th card started working.  Ahhhh thanks everyone for the help.

haggyy, try the registry patch above, then try viewing in Device Manager and disabling any devices in the same connection/folder, I'd like to hear that yours is working...