Apple lists mystery 3-meter "Pro" Thunderbolt 3 cables on Mac Pro specs sheet
Apple has included a collection of "Pro" Thunderbolt 3 cables in its list of accessories for the new Mac Pro, including the odd option of a 3-meter cable, a length that is not typically covered by the standards governing Thunderbolt 3 cable specifications.
The online Apple Store page for the Mac Pro, published on Monday, includes a section within the Tech Specs page titled Kits and Accessories, where Apple lists software, storage expansion, hardware, and peripherals that it suggests could be bought to run on the new professional workstation.
Under the "Other Accessories" category are three listings for the "Apple Thunderbolt 3 Pro Cable," which suggests some alternative version of the existing Thunderbolt 3 cables it sells with some extra element to benefit the Mac Pro in some form. The three listings are not linked to other pages, so there are no published details as to what is "Pro" about them at this time.
The three listings also indicate Apple is doing something unusual with the "Pro" cables, as the three lengths are identified as 1.8 meters, 2 meters, and 3 meters. As Apple already sells 0.8 meter and two meter Thunderbolt 3 cables, it is likely the 1.8 meter option is a mistake.
The existence of a 3-meter Thunderbolt 3 Pro Cable is odd, as the standards relating to Thunderbolt 3 specify the longest a metal cable can be is two meters and still provide full Thunderbolt 3 speeds. At present, there are no vendors of optical Thunderbolt 3 cables.
Sources of AppleInsider within Apple not authorized to speak on behalf of the company have confirmed the existence of the three-meter length, but refused to elaborate.
Active Thunderbolt 3 cables are able to support 40Gbps of bandwidth at up to 2 meters, while passive runs at full speed at up to 0.5 meters then reduces down to 20Gbps at up to two meters. It is certain that the three meter cable length in an active cable, as full speeds aren't possible at that length with passive cabling.
It is also plausible that Apple is taking advantage of some aspect of Titan Ridge, Intel's Thunderbolt 3 chipset that supports up to DisplayPort 1.4 and a fallback to USB 3.1 speeds if a Thunderbolt 3 host is not detected. The Mac Pro specifications do not clarify the situation.