Electronics question about LED's :)

OK, this is probably to u guys a totally retarded question, but im goin to ask it anyway!!

I know inside my case the PSU is supplying my hardware with 12v DC... what I doing is adding some LED's into the front, but what i dont know is what size resistor(s) i should use in order not to blow up my 5v LED's

If you dont ask you dont know, and if u dont know things go bang (somtimes)

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I just took a look at the guide on the beginnin of the forum and that proved to be extremely helpful

 

i am gona recamend this since i dont know the specs on the LEDs or how they will be wired.

 

Or you could stay here at bit-tech, if you know how to add the voltages or currents if you want more than one.
http://www.bit-tech.net/article/68/

 

And for starters assume they're not really 5V leds - blue and white are almost always around 3.6V typical. It's probably safe to run them up to 20mA, so on 12V use a 430 or 470 ohm resistor, on 5V use a 68 or 75 ohm.

 

depending on where u are gonna get the resistors from some site will sell reisitors already sized up for voltages of 5V and 12V so no need to calculate them urself..