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New PC No Longer Boots Up

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by dan_macgregor

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I built a new pc which appeared to work fine. I knocked the desk the computer was on, the pc cut out and now the PC does not start at all.

I press the power button on the case and there are no lights and no fans at all. The motherboard has a green light indicating there is power, ive tried switching PSU for one i know that works and i get exactly the same problem.
Ive also tried starting the PC from the power switch pins on the motherboard and still it doesnt start.

Im not sure what to try next, the two PSU's i have used may be a bit low power (400w & 435w), but i would have thought i would get something especially as it used to work.

Does anyone have any ideas??

9 replies

by rob miners

You may have to Bench Test it. But first make sure that it is plugged into a live socket.

First thing to try is loosening the Screws that hold the Motherboard to the Case. They will only need a full turn. Reconnect the Power and turn it on. If it powers up shut it down and retighten the screws. They only need to be firm.

Make sure that there are no loose screws or other components inside the case. These can cause shorts and other serious problems with the PC.

Also check the power outlet that you are connected to by plugging in something else and turning it on.

If it's none of the above try this Bench Test.

Carefully remove everything from the Motherboard. Remove the Motherboard and put it on an anti-static mat on a bench. Remove the Power Supply if it is a known working good one to test with. Remove the Heatsink and give it a good clean. Remove the CPU and reseat it. Reinstall the Heatsink remembering to use CPU grease. Reseat the RAM and test with one stick at a time. Connect a hard drive and the Video Card. Connect the Power supply to the Motherboard. You can use a flat blade Screwdriver to short the Power pins on the Motherboard if you haven't got a spare switch. Connect the Monitor and turn it on and see what happens. If it stars up add one Device at a time to test it.

Keep us informed as to your progress if you require further assistance.

If you think that any of the posts that have been made by all TR Members, have solved or contributed to solving the problem, please Mark them as Helpful so that others may benefit from the outcome. ;) :D

Edit: spelling

by oh smeg

Test the Power lead from the Power Socket to the Computer you may have broken it internally when you [b]Bumped[/b] the desk that the computer is on.

Other than that I can only suggest the Power Point/Socket as a possible point of failure and no matter how severe a knock that a system gets it shouldn't prevent it posting. It may destroy a HDD but it shouldn't affect the other electrical components a there are no moving parts involved to break, bend or otherwise stop working.

Check all of the Internal Electrical Connections again as this has to be Electrical Related. Also retest the PS's in the one that the other one was removed from if it's actually working that is. It would be pointless to test with a dead system.

The 400 W PS shouldn't be an issue if it is a good one as these have the same power output as something much bigger that is measured as a Peek Value so it would be equivalent to a 600 or better unit that is measured as a Peek Value of W. No Name PS's like Flower and so on are all Peek Value and their stated rating is what can be supplied only for short times then they need to cut back and cool down. The Good PS are rated to a constant Power Output and can provide the Stated Power 24/7 with Peek Values far in excess of their actual rating for short periods of time.

So unless there was something loose inside the case that could have caused a Short Circuit or the knock was so severe that it caused the M'Board to break it should still work.

Col

by dan_macgregor

Thanks for the suggestions.

Just to clarify. The PSU on the PC is a Corsair 400W model. I am confident the Power Point and power cable are ok, i have also tried other cables and sockets just to be certain.

The knock wasnt that severe, i was suprised it was caused by that.

I will re-check all of the connections on the Motherboard, and i will also try running the Bench Test suggestion aswell.

Its just wierd that it was working one minute and then stops working the next, especially as all of the components are new.

I'll let you know how i get on.

by thumbsup2

You say it was working one minute and the next minute it was not. BUT.... you "knocked' it within that minute, probably harder than you think. Why would it be weird to you you that it doesn't work afterwards? These things aren't made out of rubber. They don't bounce. A slight 'bump' can cause components to come loose, slightly out of the sockets. Have you checked any of that?

by dan_macgregor

I tried running the Bench Test and the system booted up fine. I then put the same components back in the case and it failed to start. After trying a number of different things, and cutting the story short, the problem ended up being one of the motherboard mounting screws in the case. Like most cases this case can take different sized boards. It just so happened that one of the mounting screws that i was not using was in contact with the underside of the board bridging some cicuitry that was shorting out the board. After removing this screw the system now works fine.

Im relieved as i thought this could have ended up quite expensive!! Thanks for the suggestions everyone.

by oh smeg

They do cause Short Circuits and the underside of any M'Board isn't insulated so they are likely to destroy the M'Board when they cause a Short Circuit to occur.

You got lucky this time but it could just as easily have destroyed the M'Board, CPU & RAM depending on where this unused Standoff was located. When this happens it doesn't matter how old things are the damage is done in the first Nanosecond and to be perfectly honest is far more likely to happen with New Components than with old.

This is related to Poor Build Technique's not the actual Hardware itself. :)

Col

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