Only PSU starting when i connect power cable

[Leonardo1987]

Good Morning! I have had the following problem for many months and I don't know how it started. When connecting the power cable to the PSU, it turns on by itself, with the cooler spinning to maximum speed. Heatsink coolers, graphics card and other components are also working at maximum speed. The computer itself doesn't turn on. When I press the power button, everything normalizes and the equipment works normally. This also happens when it hibernates. My fear is that this could burn some component or peripheral of the equipment. I still suspect that a TV that was connected to his DisplayPort has burned because I left the house and the PC hibernated without my seeing it, staying at least 30 minutes in this mode.

- Tested with different HDs and SSDs;

- I've already tested 3 different processors;

- Different memory modules;

- 2 different fonts;

- I already tried without the case;

- Updated BIOS to Latest Version - 03.08 Rev A

- I reset the CMOS several times;

Funny thing is that this also happens, when I turn on ONLY the power supply and the motherboard, without processor, memory, etc.

Here's a video I recorded of the problem: https://www.youtube.com/watch?v=Rl5XF-hlYb4

The computer is pretty good, but I wanted to make sure there's nothing else I could try before I give up.

I appreciate the support!

[itsmyname]

@Leonardo1987 -- what you see is "normal" for some computers. As soon as the computer detects that you have connected the power-cord, the computer powers-on, and runs the POST (Power On Self Test). 

The POST spins the fans at 100% speed (and 100% noise), to verify that the fans are working.

If the POST completes without any issue, then the computer will power-off, within 30 seconds.

Then, when you tap the ON/OFF button, the computer will start normally.

So, disconnect the power-cord. Press-and-hold the ON/OFF button, for 5 seconds, to drain any "residual" electricity. Reconnect the power-cord, and just WAIT for the POST to run, and for the computer to power-off.  Then, when you later tap the ON/OFF button, the computer will do a "normal" start-up.

[Leonardo1987]

When you say the computer turns on and runs POST, you mean the computer's POST screen, right? Who performs memory checks, BIOS input buttons, etc?
In my case it doesn't start this screen by itself when I connect the power. Only if I press the power button. When I connect the power, it just spins all fans at full speed (case fan, processor fan, VGA fans and PSU fan). Only when I press the power button that the fans slow down and the computer operates normally.
I tried the steps you indicated, but I was unsuccessful. 😞
I've seen equipment turn on by itself when connecting the power, to perform a test, but this one is very strange behavior. My fear is that this "energy" that he applies to every computer when he plugs in the power cord will end up damaging something internal. I always need to leave it unplugged when I'm not using it. Situation that makes me very intrigued.

[itsmyname]

@Leonardo1987 -- it is a matter of "timing".

1. Disconnect your computer from any electrical power.
2. Hold-down the ON/OFF button for 5 seconds, to drain any residual electrical power.
3. Reconnect the power-cord. Your computer will run the POST -- usually showing NOTHING on the computer screen, and then power-off itself.  Do you observe this, especially the fan(s) briefly running at 100% speed and 100% noise? The POST may briefly light-up ALL the lamps on the computer. The POST also checks for the presence of RAM, and the presence of a graphics-adapter. The POST probably does not do a "test" of the RAM. The POST checks for the presence of a connected keyboard, but it does not check that every key works, when each key is pressed.
4. Wait one minute.
5. During that minute, do you see any lamps that are bright? Do you feel any breeze of air coming out of the power-supply? Do you hear any noise from the fan inside the power-supply, or from the fan on top of the CPU? Look at the exhaust port of the power-supply. Are the fan-blades stationary, or are they spinning? 
6. Now, press the ON/OFF button. More lamps may light up. The power-supply's fan-blades will spin, making some noise. The fan on top of the CPU may briefly run at 100%, and then slow down and get quiet. Then, you should see something on the computer screen. Don't touch the keyboard. How many seconds after pressing the ON/OFF button, before the fans get "quiet", by themself?

What you are reporting is 100% normal, after a "complete" power-removal, as you have doing.

[itsmyname]

@Leonardo1987 -- here is a video

The computer screen shows "establishing link".

Your computer is configured to first try to use your Ethernet connection to connect to a "boot-server". That boot-server, if it exists, contains a downloadable copy of Windows. That software is copied into your computer, and your computer boots from the download.

I really doubt that this "boot-server" is the configuration that is applicable to your home network.

So, it is a waste of time to even try this option to "boot" your computer.

Enter BIOS SETUP, and "disable" this boot-option, and set the disk-drive to be the FIRST boot-device.

This will speed-up the start of the "boot" process.

[Leonardo1987]

@Itsmyname,

in fact, this is not the problem. The problem is that the power supply stays on itself forever at 100% speed when you plug in the power cord, even if the computer is turned off. When I press the power button, it works perfectly. In the test I did on video, the HD was disconnected, so it didn't reach the operating system.

[Leonardo1987]

I tried every step. Even eliminating all residual energy (steps 1 and 2), after I plug in the power cord, the PSU never turns off, as I showed in the video. I've spent more than 30 minutes with the computer this way and the PSU never shuts down. It is always with the PSU fan, VGA Card (when connected) and heatsink fan, working and with 100% speed, while the power button is not pressed. You said that in step 3 the PSU turns off by itself after a few minutes. My PSU never turns off. In steps 4 and 5, no computer led lights up. He behaves as if he has totally turned off. Only when I turn on the power button that the leds work normally. In step 6, when I press the power button, the PSU fan slows down to normal speed and the computer starts operating normally.
I work with computer maintenance at the university in my city and I've seen computers turn on by themselves after a power failure, by setting in the BIOS. But this behavior that I see on this computer of mine, I've never seen it before.
I can't imagine anything other than motherboard problems, because the same problem happens when I connect ONLY the motherboard and the power supply (no memory, processor, storage disks and case). But so far I still had hopes that the solution would come by some setting in the BIOS or some jumper that caused this change in the hardware. 😞

[BeemerBiker]

Sounds like you got a short somewhere.  A computer power supply can be turned on by bridging pins 3 and 4 pi pin 16 to ground on the ATX connector.  Look at the 24 pin connector both above and below the motherboard for something bridging the pin 3 and 4.  shorting pin 16 to ground.  II assume you tried another power supply.  Lookup bridging computer power supplies to see where those pins are.  If you bridge a power supply then you have to turn it on and off by unplugging which sounds like your problem.  

If you have an ohm meter check the resistance between those two pins  pin 16 and ground on the motherboard and on the power supply connector.

[edit] Sorry, had the wrong pin number.  

The other possibilities are a stuck reset,  stuck power button.  Not sure if a stuck CMOS clear button could cause it.  Your motherboard does not have onboard reset and power buttons I dont think.

[BeemerBiker]

I got to thinking about this and I have seen similar problems when moving a Dell, HP (or whatever) motherboard to an ATX case.  

Did you assemble your system from a motherboard and other parts? If so, the front panel cables may be needed to ensure the system boots correctly.

For example:  I have Dell 7010 bare motherboard and it powers on completely as soon as the power supply is connected.  There is no way to stop the system from booting up unless the original front panel and power cable are connected.  Alternately one can jumper wires to fool the bios into booting up properly.

[itsmyname]

@BeemerBiker -- I have Dell 7010 bare motherboard. It powers on completely as soon as the power supply is connected.  

On many computers, this is a setting in the BIOS -- "power-on immediately after the end of a loss of power".

On some computers, especially Lenovo, connecting the power-cord causes the motherboard to do a quick "POST" (Power On Self Test). If the POST completes successfully, the computer powers-off.