Unknown red switch

[hobo_man]

Hi, I just noticed that on that back of my computer, where all the wires are, there's this very small red switch under the power supply. If I flip it to one side, it says "230" and if I flip it to the other side, it says "115". I tried looking at the manual for my computer but it doesn't say what it is.
Is this some type of power switch?

(And perhaps this is the reason why my computer always restarts suddenly and saying it recovered from serious error? People told me it has to do with an uneven power supply or fan not working, which my fan works perfectly.)

 

[bla!!]

That allows you to use your computer in countries that have different Voltages running in their power lines.

Use 115 for US, 230 for other countries (check out what voltage the other country uses first)

 

[DJ-CHRIS]

115 is for North America, 230 is for europe.

 

[silence782]

DO NOT FLIP IT! It will cook a system.