You can't as bandwidth testers for cables are not cheap, the only way is to test it is with known working high bandwidth devices.
There is a lot of snake oil when it comes to video and audio cables. The reason why many monitors come with 1.5m or so short barely usable cables is that due to length they can lower quality = cheaper.
The longer a cable the better it needs to be.
I'm not sure even expensive Club3D cables are guaranteed to have the necessary full spec bandwidths, for other makers it's sure more of a marketing specs than real specs.
Sometimes they are so bad that they will use an HDMI cable for a DP cable and then yes it's DP 1.4 compatible heh but only up to 1440p 85 Hz = low bandwidth.
Sadly it's not easy to find specs of the cables themselves from their codes.
You should not use HDMI anyway if you have DP available.
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