Valves, as used in an old wireless/radio, is not used in modern computers.
Valves had a habit of generating vast amounts of heat - needing expensive cooling systems to keep the temperature at a working level. They were also very fragile - and brooke easily.
The main problem - was heat ! Valves give off a lot of heat - which, if not dissipated - would cause the valves to fail.
they were huge and you needed loads
Mechanical valves are effective but can increase the incidence of blood clots.
using valves
Probably rate of burnout and heat. But this was common to all vacuum tube computers, not just Colossus.
To many people dying and changing valves for something else
To many people dying and changing valves for something else
Reliability and heat were the main problems. Valves were fragile devices that, due to the relatively primitive way they were manufactured, failed pretty quickly. In addition to that, they gave off vast amounts of heat. This meant they needed expensive air-conditioning systems to keep their temperature down.
Valves
discrete transistors
There are no valves in a modern computer. If by valves you mean vacuum tubes, the equivalent is a transistor. Modern CPUs have many transistors/gates on their dies. The SandyBridge i7, a near-top end general purpose computer COU can have 2.2 billon transistor elements on the CPU die. Of course there are many more transistors incorporated in the logic chips, controllers and video cards in a computer as well.
what are some problems conected with computer investigations
The Colossus computer worked using one to two thousand thermionic valves.