Forgetten PC wont turn on properly

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teona.solescu

Aug 17, 2018
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Hello!
Last year I got a new PC, and left my old one in it's box, away from sun and humidity. The only thing broken was a the CPU's cooler push pins. Now that I've got a new cooler and heatsink, I tried turning the PC on. The result: one second where the lights are on, the fans spin, then suddenly turns of. And I cant turn it on unless I unplug it.

Tried disconnecting almost everything, the graphic card, the hdd, the ram, the battery, I even let it plugged it, whithout the battery.

Do you have any suggestions what could be that it wont run?
 
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Well yes, something could be broken or have developed a flaw. That is NOT to say you broke it - the unit has sat doing nothing for a while.

O suggest you follow a very systematic troubleshooting approach called Breadboarding. Look up the detail of how to do on Tom's website. I'll describe it briefly so you can grasp what the process does. Basically you remove everything from your case and assemble a bare-bones minimum set of components outside the case, mounted on a dry insulating surface to prevent short circuiting something on the bottom of the mobo. One type of material used for this was a dry clean wooden board, hence the name "breadboard". You try to start up[ the bare-bones set and see what happens. If that can't work as it...
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Paperdoc

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One possibility is the connections of the new CPU cooler system to the CPU_FAN header. Many mobos monitor the speed signal from the CPU_fan header to be sure that fan is actually working. If it fails to receive a good speed signal, it may send out a warning signal and shut down the entire system within a few seconds to prevent possible overheating and damage to the CPU. It does not wait for the temperature sensor inside the CPU chip to actually show a high temp.

Check the connection from your CPU cooler system to the CPU_FAN header. Maybe unplug it and re-connect it a couple of times carefully, being sure not to disturb other connections. As you do this, try to decide whether the connector plugs into the mobo header properly. I don't know what new CPU cooler system you have, but SOME item must be plugged into the CPU_FAN header to send it a speed signal.
 
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teona.solescu

Aug 17, 2018
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Searching through different threads from around here, i encountered this solution. As i said, only the pins of the CPU fan were broken, so i tried to turn on the PC with the old fan connected(which was performing normally before). But I got the same result with any of the fans.

What I find the weirdest about this situation si that once I connect the power cord, I turn the PC, it shuts down as described and no matter how I press the button it wont open again until I unplug and plug again the power cord.
 
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Paperdoc

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OK, I'm not clear about what is broken. A "standard" fan connector on the end of its cable or wires is FEMALE - that is, it has holes, not pins. But you say the PINS on the fan are broken. Now, some fans come with a different connector called a 4-pin Molex. It is about 3/4" wide and the MALE connector on the end of this fan's wires would have space for four round pins in a row inside a shroud, but there may be only two of those pins in place. This type of connector cannot plug into the mobo male CPU_FAN header; instead, it plugs into a matching female connector coming directly from the Power Supply Unit (PSU). Oh, and there's a third arrangement that can cause confusion. Some fans come with BOTH of those connectors on wires from the motor so that you have an option which way to use it. BUT your must NEVER connect BOTH of those connectors to a power source. Use ONE or the other, but not both.

Sp, which type of connector does your new fan have? Am I correct to understand that this is the SAME connector as your old fan had before it broke? Where is the fan plugged in?
 
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teona.solescu

Aug 17, 2018
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Sorry for creating the confusion. No wire is damaged at all, I was reffering to the "pins" which attach the heatsink and the fan to the motherboard(plastic push pins).

Both fans have the same connectors, and I plugged the new one where it says CPU_fan.

For further misunderstandings, Ill leave here the motherboard and the fans models.

Old fan:
https://www.amazon.com/Intel-D60188-001-Sock-Copper-Heatsink/dp/B001BLWS84

Newer fan:
http://www.scythe-eu.com/en/products/cpu-cooler/katana-4.html

Motherboard:
Asus P5B-E
 
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Paperdoc

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So you had to replace the entire CPU cooling unit, and now the system behaves this way. What you describe actually sounds a lot like a short circuit somewhere. The typical symptom for that is when you turn on power, it only runs (maybe just fans) for one to three seconds before shutting down. Other sources of different problems (like a missing fan speed signal) normally take much longer to cause a shut-down.

I am assuming that, when you removed and replaced the heatsink / fan system, you had to remove the entire mobo from the case to gain access to the bottom. In the process you must have moved a lot of stuff. You should re-examine all of your system for misplaced connections and wires. Look also for possible contact of the bottom of the mobo with the case's mounting plate. Especially if you remove the mobo from the case for inspection, examine carefully the placement of the metal stand-offs that are screwed into the mounting plate. These are the items that the mobo mounting screws turn into to hold the mobo in place. Compare the positions of the mobo mounting holes (and screws) with the positions of the stand-offs. There must NEVER be a stand-off anywhere there is NOT a matching hole and screw in the mobo. That's a common source of short circuits that can cause this problem. In your case it is odd that it used to work but does not now; however, check those positions carefully.

As an freak example of what odd thing can happen, let me tell you a story from my own past. I had done some work that required removal of the mobo and replaced it. As I inspected it for proper placement and alignment, I discovered a real odd one on the back panel shield surrounding all the mobo connectors. The shield had little metal fingers surrounding each connector body intended to make good contact with the outside of each connector. But on one, as the system was put together, one of those fingers got slipped INSIDE the connector body and was in danger of grounding out one of the pins in it. I had to remove the board an re-install carefully to ensure that did not happen again.

As additional items, check the newly-installed heatsink. It must be firmly fastened over the CPU so there is no looseness or wobble; otherwise the contact is not good enough to carry away the heat properly. ALSO, review how you did the replacement regarding the thermal paste. Normally for his type of operation you would have cleaned off all the old paste from the CPU chip top before installing the new heatsink. Now, new thermal paste MIGHT have been done either of two ways. You might have had to add your own, and that means you should have followed the paste maker's instructions, especially on how much to use. To little OR too MUCH is bad, so did you do that right? Alternatively, the new heatsink may have come with thermal paste pre-installed on it. BUT if that is the case, it was covered with a protective plastic film, and you should have removed that before installing. Did you? All of these items, if done incorrectly, could result in quick overheating of the CPU when it is turned on and in shut-down when the CPU's internal temperature sensor provides that information. However, that process normally takes much more than a few seconds, so that does not really match up with your description.
 
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teona.solescu

Aug 17, 2018
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Thank you fot putting so much effort into helping me and sharing all these tips and tricks.

The odd thing is that I have never removed the motherboard. Being an old CPU fan with push pins got me to only rotate the four plastic pins and get that out. One of the first attempts of repairing the PC was to make sure every cable is in place, and after seeing that wont work, I removed every component, one by one(RAM, graphic card, HDD), but again, no different result. Once I put carefully everything back in place, I removed the new heatsink and cleaned the thermal paste from it and the CPU. Aditionally, I got the chipset fully out and wiped it througly. Nedless to say it made no difference. As of the amount of thermal paste, I put, as I know it is recommended, as much as a pea. First time I spread it, but the second time, I just left the paste on the CPU to be spread by the heatsink.

Overall, I dont know if there is anything done wrong, or maybe something on the motherboard got broken and causes a short circuit. Would it act like that in this case?
 
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Well yes, something could be broken or have developed a flaw. That is NOT to say you broke it - the unit has sat doing nothing for a while.

O suggest you follow a very systematic troubleshooting approach called Breadboarding. Look up the detail of how to do on Tom's website. I'll describe it briefly so you can grasp what the process does. Basically you remove everything from your case and assemble a bare-bones minimum set of components outside the case, mounted on a dry insulating surface to prevent short circuiting something on the bottom of the mobo. One type of material used for this was a dry clean wooden board, hence the name "breadboard". You try to start up[ the bare-bones set and see what happens. If that can't work as it should, you know there is a fault in that small set of components. But if it does work, you shut down and add ONE more component and try again. You keep up this process until a newly-added component causes failure, and then you know what is "bad".

VERY roughly, the sequence of components is:
1. Mobo with PSU connected, CPU and its cooler installed with cooling fan plugged into CPU_FAN header, ONE RAM module plugged into the proper slot for a single module. Your mobo has no on-board graphics chip, so without that you cannot display anything. IF you want to try a small step first you can power up this basic setup. All it MAY be able to do is start up to the extent or running the CPU fan and, after a short time doing its POST process, appear to stop and do nothing more. IF it has its own little mini-speaker or "beeper", it may sound out a series of beeps at that point. that's as far as this can get. To actually start it up, see your mobo manual on p. 2-35 regarding the System Panle Connector at lower right of the mobo. Note that near the middle of the bottom row are two pins labelled PWR and Ground. These are where the plug from the case's front panel POWER switch is plugged in. That switch is a very simple momentary-contact switch like a doorbell pushbutton. The case front button, when pushed, merely connects those two pins together when it is pushed. For your purposes here, you need a small screwdriver to simply short together those two pins for about a second, and that should start the system up. When you have finished whatever it can do, use the PSU power switch on the back of it to turn the entire system off. Then proceed to the next addition of a component, turn on the PSU rear switch, and short those two pins again to start.

2. The next component for your situation is the graphics card. Install it in its slot and connect it to your monitor. This time it should be able to show you stuff. Turn on the monitor first, then use the screwdriver to turn on the system. It should be able to go though the POST process and then halt with a message to insert a bootable disk, since it can't boot with no OS. If you get that, you have success and can go on to the next addition.

3. Next try adding one more RAM module. If you have more than two, add more in a separate test step.

4. Add the keyboard.

5. Add the mouse.

6. Add a hard drive. At this point it MAY be able to boot from that.

Keep on going until you get a failure. IF you can get ALL of the system to work outside the case, then you will have to suspect there is a significant problem with the way the system mounts in the case that causes it to fail.

As I said, that's a brief outline. I encourage you to look up more complete details of the breadboarding troubleshooting process on Tom's.
 
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