Quote Originally Posted by Prodigys View Post
You need to put the mulitmeter on volt reading, then you take your 2 sticks of your meter with + on red wire of fan, and - on black fanwire.
But you need to look that you measure BEHIND the resistor. So the wire between the fan and the resistor is good. Otherwise you just measure 12V, and that's not what you want .
Thanks but do I measure when the PC is running or I have to turn off the power? Btw, if I have a 12V fan with 0.5A, how many ohm do I need to reduce the voltage to 8V?

I'm poor when it comes to maths and even worse when it's physics.