For utilising HDMI 2.0a/b ports, you will need HDMI cables known as HDMI Premium (there will be an orange sticker with a 3D barcode to show it is licensed to be premium.) And it will support up to 18Gb/s as opposed to HDMI 1.4's 10.2Gb/s. There are some cable that does not state that it is HDMI Premium Certified that can only support up to 16Gb/s. That cable is also insufficient.
Any cable lower than that and you will get flickering with the screen going to black and then back to the video and then black again non-stop along with seeing stars on a black background if you turn on HDR for that port on your TV such as Ultra HD Deep Color for LG on that HDMI port. I've experienced it myself.
However, you do not really have to buy those cables UNLESS you have a component such as a BluRay player or a 4K60Hz + HDR box or an Nvidia GTX 10 series graphics card for your PC that will have HDMI 2.0 to utilize the full 4K60Hz + BT.2020 10 bit HDR bandwidth.
If you are still using an old version of your 4K BluRay player that only supports HDMI 1.4 port standard, then no matter if you plug in a HDMI Premium cable, you won't benefit from using the full bandwidth of the cable. Since the player itself won't support it.
Usually, if you buy a Player or any 4K HDR Streaming Box that supports HDMI 2.0, the HDMI cable that comes will it should be able to support 4K60Hz + 10bit HDR at 4:2:2 Chroma.
