Speaking of speeding, there's a curious moment. The commonly accepted version of the PCI Express is the type of symbol Gen1, Gen2, Gen3. In fact, this should be seen as the indication of the speed to be maintained rather than the corresponding version. For example, a device that fully conforms to standard 3.1 does not prohibit anyone from working at a speed above 5 GTs.
In fact, the good PCI Express from the point of view of the developer is that it is the most direct and unified (supported by multiple platforms) way to connect anything to the central processor with minimal overhead costs. Of course, the Intel processors have another QPI, but it's a tyre that can be accessed by a very limited range of specially close companies. IBM in POWER8 is X-Bus, A-Bus and, in the future (for POWER9) - OpenCAPI, but the cost of licensing the first two is better not to think and the third is not yet available (although it should be open). And of course, direct connections through PCI Express are valid only when you want to be long, fast and slow. For all other cases, there are USB, SAS/SATA, Eth and others.Although PCI Express was originally conceived to connect the components inside the computer, the desire to connect a cable arose quite quickly. This is usually not necessary (not unless for laptops, it would sometimes be desirable for an external video card to be connected or something), but for servers, especially with the appearance of PCI Express switches, it has become very relevant - the required number of slots is sometimes not so easy to accommodate within one chassis. And with the development of GPU and computing intercontent networks, especially with the emergence of GPU Direct technology, the desire to have many PCI Express connections to one host has only increased.
The first PCI Express cable connections were standardized as early as 2007 (sheet 1.0), the second audit took place in 2012, retaining the constant type of diluting and cables. It cannot be said that this connection has been very widespread (the same niche is narrow enough), but some large Hungarians have produced both dips and cables, including active optimism. One Stop Systems is one of the best known companies offering various options for expansion chassis with PCI Express cable.
PCI Express external connection cable
However, cables (and disembark) chosen from the outset are no longer very comfortable today. The first (and rather substantial) problem is that it is not possible to accommodate the number of unloads required to remove a port of width x16 on a single low-profile map (previously, a special consignor for x16, but the use of smaller ports is lost, and this type of consignor has failed to do so). The second inconvenience is that this type of cables is no longer used.