T. Ment wrote:
My computer case green led failed. I bought some on Ebay, but they are
so bright they light up the room and obscure the other color leds.

Any suggestions for a cheap source of low intensity leds in a 3mm size?
Maybe Mouser, but then $1 worth of parts costs $10 to ship. If I have to
spend that much to fix it, I'll just live without a power led.

Can you add a resistor or something to change the brightness?

Yes, you can add a resistor.

The case wiring has a harness with twisted pairs. There
is always some series resistance in the path to limit
the current. (Because making a precise regulated voltage
to drive the LED with a voltage source would cost too much
to do.) The resistor helps limit the current flow. 20mA
is a typical design value for operating current for T1 3/4
LEDs (or so). YMMV. Check datasheet. The following diagram
is simplified so only the concept is present.

Mobo +5V ---- Rseries ------------------------- LED-FP
GND---------------------------------------

You can either pull the panel assembly from the case
(could be a small PCB that is removable) and add
an additional resistor there.

In any case, you want this.

Mobo +5V ---- Rseries ------------- Rseries --- LED-FP
GND---------------------------------------

If you're brave, you could certainly change the
resistor on the motherboard, but it would be SMT
and you'll need skillz to remove. (I use two
soldering irons for this, say a 25W and a 15W,
heat the ends of the SMT and move it out of the way.
Rotating the soldering irons as you pull them away
from the work, helps prevent the SMT from "sticking"
to the tip of the iron.)

Putting the resistor in the wiring harness
would work. You need shrink wrap (Polyolefin tubing)
to do a neat job and insulate the work. Electrical
tape is a no-no (a gooey mess).

I'd try and do it at the front panel PCB, so the
job is neat and tidy.

*******

On a computer case here, I taped a piece of "white card",
like a recipe card, over the blue power LED on the
computer, and that provides sufficient attenuation
to make the computer case "eye safe", if you know
what I mean. Now you don't need a soldering iron.

Paul