CAT6 U/UTP slimline datacenter ethernet cables are smaller in diameter (3.8mm vs 5.9mm) than regular CAT 6 patch cords. The bending radius is lower in comparison with regular patchcords. All this results in a better airflow in the server rack/network cabinet.
Although ISO/IEC and the TIA standards describe the use of patch cords between 22 and 26 AWG, it is possible to use 28 AWG patch cables. This results in a higher attenuation, particularly at higher frequencies.
ACT advises a maximum bundle size of 24 cables in PoE applications. In this case the temperature of the cables, that are delivering PoE deployments, will not increase. The standard, ANSI TSB-184-A, limits the maximum temperature increasement, to less than 15 degrees Celsius above the ambient temperature, for the center cable in a bundle.