LED lighting in a computer case.

Surge4

Honorable
Nov 2, 2013
18
0
10,510
So I've tried so many times to add leds to my computer case. However, every time I attach for example 4 LEDs in series to a 12v Molex from the PSU, they last for a day or two and fade, and at last they just burn out. Oh and they get really hot. I know righthere I'm not understanding the way they work because according to what I know, if I connect 4 LEDs in series it should be 12v (3x4=12??).
So how should I do it? And with resistors, the resistors just get extremely hot!

Oh and, is this the right section for this?