I have a power supply unit (PSU) of the old type with a 20-pin main power connector for the motherboard. Unlike most of the newer units with the 24-pin power connector this one does not have a green "power on" wire. What is the equivalent to this wire on the old PSU units?
I basically just want to check to see if this PSU is working, and check the voltages, just to rule it out as the cause of problem. But I'm not sure how to do the "paper clip test" where you jump the green and the black (ground) pins, as this one lacks the green wire.
Maybe the power is supplied on this unit as soon as I plug it in? With no need to jump wire any pins? Or is it the grey wire (power good)? What is this "power good" anyway?
How do I even tell what ATX version this PSU is? Number of pins on main connector? Color coding?
Viewing the 20-pin connector from the bottom, with the retaining clip to the right, these are my color coded wires, starting from the top pin on the left row:
- Purple
- Purple
- Black
- Red
- Black
- Red
- Black
- Orange
- Brown
- Yellow
- Purple (2x)
- Blue
- Black
- Grey
- Black
- Black
- Black
- White
- Red
- Red
The pin # 11 has two purple wires in it.
Here are some additional details from the label of the PSU:
RED +5 V
YELLOW +12 V
WHITE -5 V
BLUE -12 V
PURPLE +3.3 V
BROWN +5 VSB
ORANGE P.G.
BLACK GND
GRAY PS-ON
It looks like grey wire is "power on" and orange wire is "power good".
Best Answer
A typical ATX 20 pin PSU connector should have a "Power On" at pin 14. http://jwenet.net/notebook/2005/1161.html.
Looking at the connector face-on, if all the pin's shielding have their flat side facing to your RIGHT, then pin 14 is the 4th from the top on the RIGHT column.
"Power Good" outputs +5 V after the power supply passes its own self-test. This is typically within a second of being powered on. The +5 V then remains live until the PSU decides something bad has happened, and this tells the motherboard that the voltages may be unsafe. Without the +5 V on "Power Good", the motherboard should not POST.