Compaq presario SR 2020NX motherboard start switch pin order

one way it will work one way it wont

do you mean the "AT-ATX" connector cable to the motherboard?
if yes they are all the same http://www.smps.us/atx-pinout.png
else i don't understand what you mean (post a photo next time)
bye

The plastic front of your desktop computer is the Front Panel.

The area of contact pins on the motherboard, that the wires from the Front Panel go to, is the Front Panel header.

F_PANEL_1

The Front Panel header contains connections for the Power On switch, Power On LED light, HarDDrive activity LED light, and so on.

http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00864922&tmp_task=prodinfoCategory&cc=us&dlc=en&lang=en&lc=en&product=3339274

(Look at the motherboard photo. The Front Panel header is at the bottom right. Scroll down for the motherboard illustration )

There are 9 contact pins.
4 across the Top row, and 5 across the Bottom row.

The four pins across the Top row are numbered EVEN.

From the Left side going towards the Right side;
Pins 2, 4, 6, and 8. There is NO pin 10, just a blank spot.

The five pins across the Bottom row are numbered ODD.
Pins 1, 3, 5, 7, and 9.

A) Pins 2 and 4 are for the Power On switch

B) Pins 6 and 8 are for the Power On LED

(LED is dim when the computer is on? Switch the wires around )

C) Pins 1 and 3 are for the HarDDrive activity LED

(LED is dim when the harddrive is operating? Switch the wires around)

D) Pins 5 and 7 are for a Reset switch, IF a Reset switch is used.

How to know which wires are for the Power On switch, Power On LED, and HDD LED?

Follow the wires into the Front Panel. Remove the Front Panel, and follow them.
(Need guidance removing the Front Panel post in a Comment )

For additional questions please post in a Comment.

Regards,
joecoolvette

i had the same tower as you. there are a number of reasons why it might not work. are you talking about a dvd or a dvd drive?

Looks like it comes with a 550w power supply, so anything in that range would be fine. Below are the specifics if you need them.
Best of luck, William
-------- " Replacement power supply for Compaq Presario SR2020NX- 550 Watt Replacement Power Supply Upgrade
- One (1) 20+4 ATX Power Connection
- Two (2) SATA Connections
- Four (4) large molex connector (4-pin)
- One (1) One (1) floppy connector (4-pin)
- One (1) ATX 12V connector (4-pin)
- One (1) 6-pin PCI-Express Connection (6-pin)
- ATX Form Factor
- 575 Watt Replacement Power Supply
- Input Voltage: 100 - 240 Volts AC
- Width: 5.75"; Height: 3.25"; Depth: 6.0"
- Voltage: +3.3V (38A); +5V (40A); +12V (25A); -5V (0.5A); -12V (0.8A); +5V (2A)
SATA Support
- Supports both 20 and 24 pin motherboard. Great Power Supply Replacement or Upgrade. Compaq PSU Presario SR2020NX Power Supply Replacement"

If your computer is not switching ON you can try the following in order
1.you have to plug the power cable properly then try changing the power cable.
2. Check C P U power Button is working this can be done by opening the cabinet and switching the computer on by touching the two power button front panel pins on the motherboard with a screw driver if the computer gets started then it is the promblem with the power button in the cpu
3.Try replacing the SMPS with a new one
4. Finally change the CMOS Battery
Thanks

In BIOS boot order; you just switch them.
or
On the motherboard you switch the wires connected to the motherboard.

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Orient the motherboard so that the Memory Slots are at the top of the board as you look down upon it, and the white plastic power connection is at your left also at the top of the board.

The power switch block of pins should be at your right hand and also at the top of the board in a line with the power connection and the top of the memory Slots and identified as such, but since you have been persistent in asking, I assume they are not so carefully identified.

If you do not have the other connections assembled on the rows of black plastic with copper colored pins where the connection to power is located, simply use a magnifier to locate the paint that SHOULD be located on the printed circuit board identifying the power switch, the hdd switch and the fan power connecter and note the POWER indication located on the motherboard in white paint. The jumpers or white pieces of plastic should also be located in this area, as a guide.

Compaq does not provide such a diagram as you request, but does have a PICTURE of your motherboard located here halfway down the page in the form of two alternatives.

If it won't go past the splash screen, and you have replaced the CPU, I agree that it is probably the motherboard.
One other test you can do is, remove the memory chips, and any cards that are plugged it, and see if it beeps on start up.
If it does, count the beeps. If it doesn't it is the motherboard.
If you get beeps, plug the memory back in, and try again. Listen for beeps. Let us know what you find.

And I don't know if Compaq's do this (Dells do) when you turn it on, do the fans spin up normally? Or does it sound like a small jet? Speaking of which, do you see the fans spin up at all?