This may sound like a stupid question, but on my case do i just wire in new leds in the place of the old ones without anything added like resistors. Thanks.
depends on where you want the power too those leds to come from... if it's standard headers from a mobo then a direct swap is good... if it's anything external, use a multimeter first just in case..
if theyre blue originally, and you wire in a different color LED then youll have to add a resistor but you should be fine otherwise
The colours of the leds will stay the same and will come off the motherboard. Thanks for the information.
Not true. The motherboard does some pretty fancy internal regulation, and will correctly drive almost any LED. Think about it; the LED doesn't come with the board, it comes with the case. The board doesn't know what kind of LED it's going to end up with, so it has to be prepared to drive anything. And it's not like the non-blue LEDs in cases have resistors inline, because those colors have been around longer than the blues, and nobody changed a spec to say 'oh, and btw, motherboards are rated to drive blue LEDs now.' I actually replaced my blue case LEDs with green and yellow a few weeks ago, and with no resistor or anything, they are being driven correctly. Since you said you were staying with the same color, I realize you don't even have to worry about that stuff. However, bear in mind that your motherboard will correctly drive pretty much any replacement LED. You couldn't use something ludicrous like a Luxeon, but for normal LEDs you'll be fine.
crazybob's right, the motherboard does some witchcraft so it wont asplode your LEDs, most if not all will also have a 100-300 ohm resistor in the current path anyway, just an extra level of security I suppose.
thank you crazybob for correcting me or else i would of never known. i just thought that the case manufacturers used those Led colours because of voltage reasons.
You're quite welcome; that's what these forums are for - sharing ideas and learning new things. That's how I learned it, as well - before I swapped mine, I posted a thread asking if changing the LEDs would cause me any problems.
????????????? Unless I'm mistaken, you guys are completely missing it. Most LED's have a safe working voltage from about 2.5v (min) to 4v (max), with around typical working voltage of 3-3.5v. Someone correct me if I'm wrong, BUT! Doesn't the mobo header put out 3.3v? That should drive most normal LED's, right?
You are indeed wrong. The majority of LEDs other than white and blue have a maximum forward voltage of 2.5 volts, so if the motherboard header does nothing more than let loose with 3.3 volts, anything other than blue (including the yellow and green I've been running constantly for weeks) would die almost instantly. Look in the thread I linked from my last post; some of the replies in there are very in-depth. The motherboard doesn't do magic to provide exactly the correct settings for each LED, but it does something a whole lot more complicated than giving a predetermined voltage.
i'm about 90% sure that the MB outputs 3.3V and then its up to the case manufacturer to throw in the correct resistor to limit the current going to their specific LED. just because you can't see the resistor doesn't mean that its not hidden behind some panel. and you probably wouldn't notice if you changed from a green to a blue. the blue led would just not be as bright as it possibly could. i can't think of any way to implement your "fancy internal regulation" without the use of a photodiode to detect the light emitted from the LED.
In truth, I think it's very straightforward - the indicator LEDs are fed through a current limiter. High-voltage LEDs are conveniently also high resistance. Therefore, with I=V/R set constant for the board, the voltage fed to an LED will vary proportionally with its resistance. The board also has a limiting resistor of 220-330 ohms, which needs to be included with R in that calculation. I'm not going to dig up actual values, but essentially, if you hook up a high-resistance LED (blue), it'll be fed a high voltage. If you hook up a low-resistance LED (yellow or red) it'll be fed a low voltage. There's actually no detection, monitoring, or magic involved - just physics. Additionally, if you'd read my earlier posts you'd have noticed that I actually switched my blue LEDs for yellow and green ones. The yellow ones have a low maximum forward voltage and will fry almost instantly at 3 volts (I fried a few playing around), and I can promise that they don't have hidden resistors. I had the entire LED assembly and wiring removed from the case, and I did not add any resistors. In my experimenting, the yellow LEDs fried in under a second with 3 volts, but have been working brilliantly for two weeks connected directly to my motherboard. I know two weeks isn't a long-term reliability test, but given how quickly they fry, the fact that one has been sitting here indicating hard drive activity for weeks means something - if it had been fed 3.3 volts, the hard drive activity during the very first boot would have toasted it. Even if other cases have magically hidden resistors, mine doesn't, and works.
well, i wasn't aware of the difference in the led resistances (thought they required different currents)... so i guess it is very plausible to vary the voltage with the different LEDs. and i apologize for not correctly reading your post. but i'm still skeptical... what if the resistance on the board took worst case into consideration and put a resistor there to ensure a blue (or white) LED would go forever and a green/yellow LED would only glow at half-brightness. i guess i'm wondering why the MB manufacturer would spend all that money/time/board-space on a current limiting circuit...
