LED's - are red LED's the only ones that can run below 3V?

[Jeff7]

The LED headers on my 8RDA+ put out 2.58V; it seems that only red (and yellow, though just a little dim) will light up brightly on this voltage. The blue and white LED's I've tried won't light at all; mileage varies among green LED's - the diffused lens ones I have light up like the ones on CD-drives - they light up; not bright, not dim; the clear-lens green LED I've got just lights dimly.
Do they behave like this simply because of the chemicals used in them to create the different wavelengths? Is there some way of upping the voltage a bit?

Edit: I checked the headers for amperage; that's only at 10.1mA.

 

[wynlyndd]

tranformers can change voltage...but is it really the voltage or is it the amperage?
(I am not an electronics expert)

 

[HiTek21]

LEDs should light up even if its under powered(to a certain extent) but it may not be as bright as you want it to be. LEDs are tricky you have to make sure they are installed correctly otherwise they wont light up because diodes only allow current to go one direction, Anode of the LED is Positive and the Cathode is Negative.

Most LEDs are rated at 3.7 volts @ 20mA (Diffused or Clear) but they should be able to run at 2.5v. I've been able to get LEDs to run on 1.4 volts.

 

[Jeff7]

These things are picky about voltage, I'm pretty sure of that. Some of these LED's that won't light with the motherboard will light with a 3V lithium battery; others will only do so dimly.
I've messed with LED's for a few years now, but of course, I've not had much experience with the newer high-intensity ones, as they're newer, and more expensive.
I'd tried the stubborn white/blue ones (rated 3.6V-4.2V) both ways on the motherboard; they won't light either way; some will light, but only just barely enough that you can see if the room is dark. But the one red LED I have in now as the HDD indicator is rated for 2.1V, but it's blinding to look in to when it's on.
That 2.58V figure comes from a voltmeter - I tested the headers themselves with it, and it held very steady at that voltage; that was without the LED connected of course.

 

[HiTek21]

I connected a couple 5500mcd blue LEDs to my mobo HDD & Power LED connectors which only put out about 2.85v and they are bright as ever.

 

[Jeff7]

Ok, previous statements retracted - I'm reading about 10.1mA coming out of the power LED header.
So I've got only 2.58V @ 10.1mA. Now what? Look for low-power LED's if there is such a thing?

 

[Mark R]

You won't find a blue or white LED which will operate below about 3.3 V due to the physics of how LEDs work.

You don't have much option here, either you stay with conventional red/yellow/green LEDs, or you add a transistor to switch a higher voltge circuit on and off.