Green light behind motherboard blinking when power is connected

The green light with "CR3J1" beside it on your Dell Dimension 4700 is most likely an indicator for the power supply. The "CR3J1" is a code for the power supply model number. The green light indicates that the power supply is functioning correctly and providing power to the system.
If you are experiencing any issues with your system, it is recommended to contact Dell Support for further assistance

That sounds like the backlight inverter board. Check ebay HELP NUMBER +1 833 272 0777for the board or a repair kit for it.

This is a system fault but unfortunately,you may have to replace either the power or motherboard depending on whether the green LED blinks continuously or completely dead

This is an easy fix so here you go nice and simple:

Problem: Your motherboard circuit has been cut.

Causes: Power disconnected during operation. Power outage or short in the surge protector.

Symptoms: Flashing green light on both motherboard and power supply. System will not power on.

Solution:

Step 1: Ensure that both the power supply and the motherboard lights are flashing green, not solid or off.
Step 2: While the power is on, disconnect the power supply from the motherboard. This connection is the largest of the connections and should be listed as the 'P1' or 'Primary' power connection.

Step 3: Wait until the green light on the motherboard stops flashing and check to ensure that the green light on the power supply is now solid. If it is not solid, disconnect the power to the power supply and wait until the light turns off completely. Then reconnect, it should be solid now.

Step 4: While the power is on, reconnect the P1 connection to the motherboard and you should now see that the light on the motherboard is solid.

Step 5: Power on your PC. The problem should not persist.

Warnings: If the power supply light remains flashing after you have restored power to it while it is disconnected from the motherboard, it may be a system failure in the power supply itself requiring replacement. Always be careful when working with an active or live power machine.

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Remove the side pane to access your motherboard cables, etc. Locate the connector on your motherboard that contains the wires going from your power supply to your motherboard. It will be a large, rectangular connector with a lot of individual wires It is not a ribbon cable but should be located next to a ribbon cable connector and next to a green blinking light on your motherboard (when the power supply is plugged into the wall). Note: This green blinking light is in addition to the green blinking light on the back of the PC.

This next step is important: You have to disconnect the connector noted above from the motherboard WHILE the power suply is plugged into the wall. Wait a few seconds and plug it back in. The blinking reen light on the motherboard should now be a solid green light. The PC should now power up.

If the steps above don't work you will need to get a new power supply.

Try a different known working power supply on that computer, the green light on the power supply should be constant and not blinking. The green light on the motherboard shouldn't be blinking either but if its not getting the right voltage from the motherboard then it will blink as well.

Get a different power supply and see what happens. At that point the power supply green light should be constant, if its not then your motherboard is faulty at that point, if yout the green light is blinking on your motherboard, if both are constant then reseat the memory and CPU and only have the power supply hooked up to the motherboard and not to anything else.

If you still can't get video then at that point you know the motherboard is definitely bad.

Chances are your power supply and computer is fine! From other forums on this problem (which I also had), I've learned the following:
1. If you unplug the computer for a half hour or so (the blinking green light will gradually slow down and quit) and plug it back in, the situation will correct itself and the green light will be steady; however if this does not work,
2. a reset that works for a lot of people with the blinking light problem involves leaving the power supply plugged in and unplugging the power supply connection at the motherboard (it usually also has a blinking green LED) and plugging it back in. To read up on how to do this, Google "blinking green light on computer power supply" and read through some of the forums and you'll come on more specific instructions. Usually, you have to wade through everybody telling you to replace the power supply or your motherboard is fried. It's worth a try for a quick fix, just in case those situations don't apply!

I've had that happen twice to my Vaio desktop and there was a very easy fix. I'm not a techie, but I found a recommended solution online when this first happened six months ago. I couldn't find the solution again, but I fortunately remembered the steps.

Remove the side pane to access your motherboard cables, etc. Locate the connector on your motherboard that contains the wires going from your power supply to your motherboard. It will be a large, rectangular connector with a lot of individual wires It is not a ribbon cable but should be located next to a ribbon cable connector andnext to a geen blnking light on your motherboard (when the power supply is plugged into the wall). Note: This green blinking light is in addition to the green blinking light on the back of the PC.

This next step is important: You have to disconnect the connector noted above from the motherboard WHILE the power suply is plugged into the wall. Wait a few seconds and plug it back in. The blinking reen light on the motherboard should now be a solid green light. The PC should now power up.

It worked twice for me; I hope it works for you.

I had the same exact problem for the same exact reason. Plug the power cable into the back. Open up the side of the case and unplug all the wires that the power supply plugs into. The motherboard, harddrive, cd & dvd drives, everything. wait about 10 minutes and plug them back in, plugging the BIG cable that connects to the motherboard back in LAST. This will make the light go from blinking to solid. I think it is a safety? to protect the motherboard from damage.

Your MotherBoard has 2 LEDs in the lower right corner, each designating a power condition. They are labeled LED14 and LED21. LED14 lights when there is a power source connected. If this is the one blinking it likely indicates a failed power supply. If you have an alternate power supply available that is comparable in power supply capabilities I would try that. LED21 lights when the system is powered on. Replace the power supply.