It's easy when sitting at your computer at home to marvel at the the myriad of uses that the same machine may be put to in performance-related technology. However some thoughts need to be imparted about this.
Mission critical systems
In computing, computers who's malfunctioning could mean a loss of profit, or even life, (i.e. you really don't want them to go down on you} are known as mission critical systems. These range from computers running transport systems to computers in the medical profession to military hardware. Two motos from our experience with computing in performance are "If it can break, it will break.." and "backup backup and backup".
The problem here is that most domestic computer hardware is designed to be as cheap as possible, to be set-up or re-set-up occasionally and transported with care. Contrast this to the environment of a touring theatre, where hardware is pulled apart, often hurriedly and probably a little roughly, thrown into the back of the van driven to the next location, while being left overnight in a cold parking lot allowing condensation to form on the electronics to then being hurriedly assembled and then expected to work faultlessly.
From experience: Some things that often go wrong and what we do to avoid them
Software compatible issues
In our experience the main cause of issues with the computer system. Our computers all have disk cadets for the main system disk and we carry a number of system disks for each system. The system installation is the bare minimum required for the computer to run. This reduces the risk of software interfering with the systems performance. We never install other software such as antivirus or spyware software on these disk as this will effect the system performance. When running with these 'performance disks' the system is just used for performance and rehearsal and never connected to a network. This essentually keeps them sterile. Cadeting the disks also allows quick disk replacement should one fail, an occurance that to my experience generally occurs on power up rather than during actual use.
Plugs, (pins bend), Leads (internal damage through repeated strain)
We rack gear up to reduce the amount of cables being connected and reconnected. This reduces wear on connectors and cables alike and speeds installation and get in times. Racking has to be done with a mind to how future developments might require additional space etc. Additionally we carry spares for all leads external to the rack system.
PCBs delodge in transport
We house our computer systems in 19" rack cases with very good ventilation, (important for quietness) and with PCB clamps. This both stops PCBs from falling out and stops them moving around or vibrating in trasport both of which could damage the motherboard.