In some trading floor/control room situations it is sometimes useful to be able to have a significant physical separation between the base unit of a PC and its screen/keyboard. This is well known as KVM technology. Some of the reasons for doing this can be security issues, lack of local cooling, space constraints or the need to eliminate the noise of PC fans.
We've built trading floors where all of the PCs are located in a locked technology room with UTP CAT6 cable extension to the trading desks. The design reduced heat and noise at the trading desk and it also eliminated a lot of under-desk equipment. We introduced structured cable patch panels which gave us the ability to quickly move individuals while retaining access to individual PCs. The IT infrastructure allowed for "hot desk" sign-on, but in some cases it was more convenient to allow a trader to always use the same (remote) PC.
In some cases it would allow the PC system units to be located where "free cooling" is readily available, thus reducing the need for investment and operational cost of air conditioning.
Matrox provide specialist technology such as the Extio and Avio systems which will deliver a fast delay free KVM extension for up to 1000 Metres over single optical fibre. They can support multiple screens, mouse, keyboard and USB. These systems are not necessarily cheap. A single pair of units for a system is in the region of of £2000 depending on the capability, but in some circumstances this is the most economical way of meeting the need.
For trading floors one of the other players is Wey Technology. There is a large price tab, but these people are widely used and have loads of experience in trading room and control room environments. Similar results can be achieved with desktop virtualisation and/or thin computing, but it is not always the most appropriate business/technical solution.