Remember, 99.99999999% of the LEDs you guys buy all have voltage drops of under 5V. This means that you should always use the 5V line and not the 12V line if you are connecting in parallel. You are just dissipating unnecessary power by using the 12V line. A LOT of extra power.

Also, usually, you'll want to connect your LEDs in parallel. Most of the brighter green and blue LEDs have voltage drops between 3.3-3.8V. If connected in series on a 12V line, you could only use about 3-4 LEDs. Standard red LEDs have a 1.6V drop, but no one uses those for modding.

Tip: Although resistor calculation is rather simple if you know about electronics, if you don't, it's not completely straightforward. Use metku mods LED calculator. This will help you.

Here is a link for Metku's Led Resistor Calculator: Here

Thanks for the tips bro...I was wondering how I could find the current(amps) of an led?

They should be listed wherever you buy them. Ask for a spec sheet.

Usually, the current should be 20mA. So if you go by 20 mA, you should have no problem.

K thanks.

ya i hate it how my blue leds have a voltage of 3.5v and my red ones are 2.0v

^^ Good point.

If you're using differnet colors, be sure to use the proper resistors so that there the voltage drops are in the range of the LEDs normal operating voltage.

Warmer colors have lower voltages than the cooler colors.

Ive noticed that a lot of tutorials on LEDs and resistors talk about ohms when it comes to picking out the right resistor, and many of the calculators only calculate ohms. But dont you have to take into account the wattage rating of the resistor as well? Im not sure how severe it might be if you would exceed your resistors wattage handling capabilities....

That's why I point out to use the 5V power source and not the 12V like some modders mistakenly do.

Also, the LED calculator listed above does indeed take into account the wattage.

EDIT: POWER = WATTS