One of the other big pools of unseen computer power is made up of mainframes, usually IBM mainframes.
These machines were the original supercomputers and until the arrival of the mini-computer and then the PC were the mainstays of the computer world. "They are still being widely used in particular segments such as finance, retail, health and government," said Jim Porell, an IBM evangelist for the machines.
When we get cash out of an ATM, said Mr Porell, it will be a mainframe that will handle the back-end data processing of that transaction. Book an airline ticket and choose your seat on the plane and chances are that you are unknowingly using a mainframe.
The machines are being used because they are used to running constantly at nearly 100% capacity. And, said Mr Porell, they have other advantages over Intel-based racks of servers.
One IBM System z10 Enterprise Class mainframe, the biggest, is equal to 1,500 Intel servers and occupies 85% less space.