Good day Mercato353,
I cannot comment on commend on the cables you have since we do not have experience with them.
Connecting 6 screens in 1080p @ 60Hz thru HDMI to a CGAX-7856M6 should not be a problem.
Please check if the hardware functions correctly
Screens, just swop cable from 5th to 6th screen
Cables, just swop 6th cable for 5th cable
Ports on VGA Card, just swop cable from port 5 to 6
Make sure Windows (vista or newer) and Bios of the mainboard are updated.
If all hardware functions correctly, then i do believe you will need at least one cable with higher quality than you have now. Most probably there is a problem with the “digital handshake” which is why windows does see it but refuses to activate it. Again i cannot really judge the cables you have now because we did not test them. But since you have 5 screens working i am confident that 1 * CAC-1153 would do the “trick”.
We of course did test extensively with our CAC+1153 and CAC-1101 cables and we found that when connecting 6 screens, using 2 x CAC-1101 and 4 * CAC-1153 work the best.