Friday 3rd April 2015: 1.55am.
Anyway, just in case anyone else has their power LED - or any other LED - suddenly die on them let me tell you what you actually need to fix this. You will need:
1. A RGB common cathode LED which have four pins, preferably with a forward voltage of 3.3v and ultra bright (14000 mcd). I ended up buying fifty (yes, fifty) of these from Amazon for £3 after I foolishly wasted €12 at Maplin buying a crappy "super bright" LED with some resistors and cable. Their "super bright" LED barely made 3000 mcd :(
Speaking of drive resistors, you don't need those for motherboards as motherboards already have LED driving resistors. I didn't know this as it's not documented anywhere, so I ended up buying a 1200 resistor pack I didn't need in the end from Amazon for £5 :(
2. 2.54mm Breadboard jumper wires, these usually come in packs and you want the all female kind. 40 for £2.
3. Breadboard mount pins, these come in long rows with a plastic spacer, same as the panel connection pins sticking up from your motherboard. Hundreds for £2.
4. Pack of heat shrink tubing of 1mm to 8mm, preferably with adhesive. This stuff is surprisingly hard to find at a decent price, I ended up ordering from DealExtreme in China which added a month of waiting. Still, from DealExtreme it was only €3 for 5m of various diameters, and besides, heat shrink tubing is very useful to have around, it has a multitude of uses.
5. Heat source. As I was ordering from DealExtreme anyway, I picked up two cheap turbine type refillable lighters/creme brulee type burner device, the ones with the long blue very hot jet engine type flame. Each cost €5 or so.
What I then did was to shrink the 1mm tubing onto each of the four pins coming out of the LED to stop them electrically contacting anything, and then attached four of the breadboard jumper wires, using more heat shrink tubing to hold everything in place. As the leads were short, I used the pins to bridge to another four breadboard wires, again using heat shrink to lock everything into place (you can see that in the third picture). Finally, I simply wired up the ground, suspend pin and power pin to the correct pins on the motherboard and voila, we have a new dual colour power LED. And all without soldering, which I find tedious.
The Antec Solo case below takes standard 5mm LEDs and has a clippable LED holder, so it's very easy to replace. But then it was an expensive case designed for a lifetime use (and is so amazingly silent, I just love that case - the machine is so quiet I can't tell if it's on without the power LED, hence the need to replace the failed one). Other cases may not be so easy to modify like this. Also, only very recent motherboards have the pins for dual colour power LEDs, so check that too.
The key points to take away are that (a) normal LEDs from Maplin are crap and just not bright enough, plus their markup is ridiculous (b) you don't need driver resistors for motherboards as they're already on there, just connect the naked LED though do try for the 3.3v forward voltage kind, else probably a small additional resistor would be wise (c) once you have the equipment, this is a very easy mod and it leaves zero doubt your machine is either on or sleeping or off.
Anyway, after all that waiting around, I am pleased. I had been accidentally turning off the computer because sometimes it takes a while to wake from sleep, and hitting the power button a second time does an emergency shutdown. That was losing me work :(