Stupid Voltage Question

[Ruckus]

I know its prolly in the FAQ but I dont see it.

The 3 pin connections on the MB for fans

pin1 (black) is neg
pin2 or center pin (red) is ?v
pin3 (yellow) is ?v

i know one is 12v and im not even sure if the other is 5v or 7v my tester is dead and im in the middle of working on something.

 

[boardsportsrule]

on fans
black=ground
red=12V
yellow=rpm sense


off psu
black=ground
red=5V
yellow=12V

 

[DJDishwateR]

I believe it strictly for RPM monitoring.

 

[boardsportsrule]

rpm sense= rpm monitoring

so on you rmobo you can see what RPM it's operating at...

 

[Ruckus]

ok thats what i needed to know i was hoping the third was 5v so i could use an LED without a resistor, right off the fan.

 

[mwarps]

Originally posted by Ruckus
ok thats what i needed to know i was hoping the third was 5v so i could use an LED without a resistor, right off the fan.

You can but it will fail probably within a month unless it's rated for 5V. They have rated voltage for a reason.

 

[mattg2k4]

If you connect a 5v led to 12v, I think it's failure will me measured in tenths of a second, not months. When you exceed the rated voltage, current begins to increase exponentially, just take a look at the current curve for any diode. So exceed it by a volt, and it might live for a while, but any more and it will die very, very quickly.

But it isn't hard to put on a resistor, there are calculators all over the web now to see what value you need.

 

[Ruckus]

it wasnt a matter of finding a resistor I just didnt feel like going out. Im in lazy ass mode today.