'How do I know if it's working to full capacity , what should I see if it's not working to full potential? Thanks' - unlike an analogue signal there are no 'degrees' of working with HDMI, it either works, has very obvious problems (sparkles, drop out, pink hue...) or it doesn't work.
The bandwidth of the Source signal plus the length of cable you require both play a part when it comes to a cable working (or not) in your system.
For anything 8m or longer we supply/recommend our RuiPro Hybrid Fibre cables.
There are many brands of cables advertised but most over distance do not pass 18 Gbps video signals.
My Recommendation to you is based on the problems I encountered. In respect to cable length of 15ft/4m to 50ft/15m a majority HDMI coax cable
do not performed to the specifications! They fail to support the HDMI 2.0b / 18 Gbps video signals! Therefore, to save you from going through same problems I encounter buy
the HDMI Fibre Cable RUIPRO 4k60HZ HDR, it is a great product available in number of length sizes. FYI My setup :
JVC DLA-X590RB/X5900 4K is the display/projector device; where the RUIPRO HDMI cable is connected directly from the output of Yamaha RX-A3060, to source player Panasonic
DMP-UB900 4K UHD HDR Blu-Ray. The Panasonic Blu-Ray player is setup to output the video content upscaled to 4K UHD, 60 FPS, HDR, BT.2020, with 4:2:2 chroma subsampling, and 12-Bit colour depth; thereby using the full 18 Gbps video bandwidth. The image is great without any problems related to video bandwidth.