Originally Posted by ukballer1012
And, while the computer was on, one red (which looked sort of pink) read 5.00V, one yellow read 11.5 V, and one orange read 3.20V.
Yellow wire identifies the defect. Others see specs (ie 10%), but forget to learn other factors that must be combined with those spec numbers. At 11.5 V, the 12 volts is completely defective.
So what is the reason for that defective voltage? In simplest terms, two factors. Either excessive load or an internal PSU defect.
For example, what happens when the same voltages are taken with only a video controller removed? Does the 'removed' 12 volt load increase that voltage to an acceptable number? Then the PSU was probably always undersized when purchased. Another often misunderstood fact. Defective power supplies can even boot and run a computer for months. Maybe the PSU was defective many months ago. However, your numbers are reporting a defect on the 12 volt supply either due to a PSU defect or excessive load.
If replacing the power supply, first learn ampere numbers for each voltage (3.3, 5, 12). A new supply must have ampere numbers at least equal to existing 3.3, and 5 numbers. But 12 volts may need a larger ampere number. Don't waste time viewing watts numbers. Important numbers are amperes for each voltage.