computer vs heater coil comparison If I have a computer and a heater coil that consume exactly the same amount of energy, which would be more efficient at heating my room?  This is assuming that they both have the same fans and heat dispersion characteristics.
And if the answer is that they are the same, then why don't we change all of our personal household heaters into computers?
 A: They are almost identical.
If the incoming energy is the same then all you care about is how much of the input electrical energy can escape from the room - everything else will become heat. Even the fan noise becomes heat when the sound energy hits the walls.
The only part that potentially can escape is microwave emissions from the CPU clock.
Computers are just slightly more expensive than electrical heaters
A: I would second Martin Beckett.  From a physical standpoint, it is possible to claim that the heater is optimized to generate heat in the best part of the spectrum, but at the end of the day, if the goal is to just heat, then the heater is more cost effective.  However, from an economical point of view, the utility of the computer is greater then the heater, so you might just be better off buying the computer on and leaving it on when the weather is appropriately cold.
A: I would third Martin Beckett and second Hal Swyers. In fact I have a server that I keep in the cupboard under the stairs, and it does an efficient job of heating this space. For example if I want to dry my shoes I will leave them on top of the server. This saves me the cost of running a heater just to dry my shoes, and serves my web sites at the same time.
From a practical perspective, computers aren't optimised as heaters and they tend to be bigger, noisier and more expensive than heaters that are designed to just heat the room. Although I could use the numerous computers scattered around my house to heat it, it makes much more sense to just turn on the gas central heating.
