Computer console turns on but nothing else happens

[Chris3843]

Hi, I am having a serious problem with my desk top. The other day, a fuse blew in my house cutting power to my computer (my computer was plugged into a surge protector). When the power was back on and I tried to turn it on, the console would turn on i. e. all the fans would spin, the lights would turn on, but my monitor got no signal, my mouse did not turn on, and my keyboard did not light up. After turning it on and off a few times, it turned on and all the sudden worked like normal. Then, today, I turned it on and it did the same thing as before and I cannot get it to work. Any help would be greatly appreciated. Thanks.

[Lisa_maree]

Hi

Do you have a multi meter?. If you do power the computer up and check all the power supply voltages. If you don't have a meter then perhaps try a different power supply. Also check the cmos battery or replace it.
If neither of these ideas are  possible then perhaps some more detail about the computer like the age and components would help to pin point the problem.

Lisamaree 

[DaveLembke]

If you don't have a meter then perhaps try a different power supply.

Lisa_Maree is correct that its more than likely a power supply that has been stressed due to the nature of how the power went out to the computer, and I'd bet on the Power Supply being the problem most likely. CMOS batteries have been known to weaken and cause issues, but these symptoms are most likely related to a weak power supply unit that is not up to the correct voltages to operate correctly. On the occasion that it does operate it is most likely running on lower than proper voltage, and continueing to operate it with a weak power supply can lead to data corruption on the hard drive when data is written under a weak power state.

Usually the nature of a weak power supply booting a computer is that the initial cold start the voltage(s) are low and not high enough to boot the system since its below the drop out voltage of the electronics. If you shut off the power supply quickly and then turn it back on within 5 seconds of which when it was shut off, the power supplies voltages come up (float) to closer to what it should operate at more quickly because the capacitors in the power supply may not have completely drained from the previous power up, and so the computer may then boot, but under a weakened voltage state.

* I had a power supply that acted like this about 2 years ago, and what I found is that the 5 Volts started out at cold boot around 4.7VDC and then creeped up towards 4.92VDC. If I powered it down and turned it back on quickly ( less than 5 seconds ) the 5VDC then read 4.83VDC and came up to 4.92VDC sooner. The computer would then boot, but the power supply was still weak. I replaced this power supply with a new 460watt power supply and my 5VDC measured 5.05VDC pretty much right at boot and held steady +/- .02VDC which was a nice strong 5VDC.

[Chris3843]

thank you both. I will borrow a known working psu from a friend and try it out and let you know how it works.

[Chris3843]

so I installed the psu and the same thing happened. do you think this could be a motherboard problem?

[DaveLembke]

It appears that the motherboard is not getting to POST to start the Mouse and Keyboard controls. Assuming the wattage on the replacement power supply unit is plenty for the system,  You could have something pulling down the motherboard.

What is the make/model of your computer or if its custom built what are the specs, and what is the wattage indicated on the power supply unit?

If you have a video card installed and the motherboard has integrated video available, I'd remove the video card and try to run it off integrated and see if the problem goes away. * I have seen many times in the past where an off the shelf computer is purchased and a video card is added and the power supply is not properly rated for handing the increased load. It may work for a while and then the power supply weakens and causes these problems. If the video card is removed and integrated video is available since it was manufactured without a video card installed and it starts to behave without any problems then you need a higher wattage power supply (usually) but sometimes can be a troubled video card. Motherboard failures like this are rare and sometimes happen, but I dont want to claim its a bad motherboard just yet until process of elimination of other factors that can cause this are checked.

[Chris3843]

i have a custom built computer.
msi z77a-gd65 motherboard
i5 2500k overclocked to 4.2 mhz (watercooled)
gtx670
500gb hd with 120gb ssd
8gb ram
750w psu
windows 7

Thanks for your reply!

[DaveLembke]

Thats a heavy overclock. Can you bring it back to native clock for memory and CPU and normal voltages when it does boot normal and see if things behave or continue to act this way?

[Chris3843]

the system will no longer boot so i dont think i will be able to change the clock speed. however sometimes the computer will boot to the bios and i could change it then. that only happens rarely though. with the cpu being water cooled im not sure if it could cause much of an issue. when the computer ran the core temps stayed at a steady 40-45C.

[patio]

The PC does NOT need to boot to change your clock speeds...remove all power to the PC...pull the CMOS battery off the MBoard...wait 5 minutes and replace it.
This will re-set the BIOS to it's defaults.

[Chris3843]

Thank you patio. I did this and the computer did what it had done before. however, not only would nothing turn on as before, but the computer would turn on for a few secs, then turn off. it would then turn itself on again, then off... The computer has done this before a few times so i dont know if the cmos battery may be bad?

[patio]

That being said replace it..Part # CR2032 available anywhere...
However i suspect serious hardware issues...either the MBoard itself or the PSU...

[Chris3843]

ya i think you are right. I am leaning towards this being the motherboard. I know it is not the psu because I tested that before. The next step for me may be trying a new motherboard.

[patio]

You did swap in a known good PSU already to test ? ?

[Chris3843]

yes i did