> > Yellow is +12 V, red is +5 V, black is ground.
> >
> > (And just in case you were curious, orange is +3.3 V, blue is -12 V, and white
> > is -5 V.)
>
> my cable only have 4 pins.. Yellow, Black, Black, Red..
>
> no blue, orange or white..

No worries... they're actually on the ATX motherboard power connector. You can splice into them, if you feel brave... :^) No need to though. +5 or +12 will run anything you need.

> and what about the ampereages ? now many mA or A goes through each pin ?

Check your power supply. The sticker should have maximum amperages or wattages for each line. If it's watts, divide by the line volts to get the amps: 60 W on the 5 V line is 12 A, while 60 W on the 12 V line is 5 A.

> > > also, how many volts a regular computer LED use ? (the same as power, HDD
> > > working, and etc..)
> > Depends. Probably 5 V, though.
>
> depends on what exactely ?

The manufacturer, the specs of the LED, among others. I remember frying an LED when I was twelve, but I don't remember how many volts it took. I think it was more than 12, though. In any case, 5 volts is almost 100% safe.