Blizzard Entertainment, the creators of World of Warcraft, are selling off old hardware in aid of St. Jude Children's Research Hospital in Memphis, Tennessee.

The 'world' of World of Warcraft is actually composed of a large number of Realms - identical copies of the game world running on separate hardware. This helps to keep the load on individual servers to a manageable level so that users can play the game smoothly, but it also means that if you want to play with friends, you have to choose the same realm when you start the game.

Having recently upgraded WoW's servers, Blizzard has decided to auction off the old servers. These are in the form of "blades" - single circuit boards that contain all the hardware necessary for a server, including processors, memory and storage. Each realm is powered by a number of blades, to provide redundancy in the case of a failure in a single blade.

The auction is being held on eBay, and features server blades from both European and US realms. The starting bid for all blades is $100, and the current highest bid is $510 for a blade server that ran the "Daggerspine" realm. You can see the auction here , and find out more about St. Jude Children's Research Hospital here .

We can see bids going far higher, as many players become attached to their realms. Not all realms are equal: some enforce a PvP (player versus player) ruleset, so that players can attack each other without penalty, while others are strictly PvE (player versus environment). Others have a Role-playing ruleset, which encourages players to play "in character" whilst in the game. Realms are further split into European and US realms, catering to each timezone. As a result, realms develop their own culture over time, depending on the players who inhabit them.