Now, it's time to check what our components are actually receiving. While the computer is on, grab an extra molex conector. This time, the ground wires are the two in the middle, the 12V is the yellow wire, and the 5V is the red wire. Put the negative (black) probe into either of the grounds, and the positive (red) probe into either the 12V or 5V plug. This will give you a reading that will show you what voltage each component that runs off that line in your system is actually receiving.
Below are some shots of this technique in action. As you can see our voltages are almost right on.