Alright i got one of those 12volt 8.3mm leds and i drilled a hole and put it in my front bezal but when i plug it in the computer won't turn on i have a red wire and i yellow wire. The red one is connected to a yellow 12v wire and the yellow one from the led is connected to the black ground one. Any ideas on why this won't work?

Has to do with AMPerage, it must be made for cars and the lowest fuse on a car is something like 10-15 amps which a regular PC psu cant deliver

LEDs do not need that many amps. They only require a current on the scale of tens of milliamps. Based on the link in the other thread, this LED requires 30mA.

Most likely you have the polarity reversed. Radio Shack doesnt really supply much online for it, but check its packaging to see if the + and - leads are indicated. If thats not the case, it might just be a bad LED.