[reny410]

hi, around these days, my PC often fail to boot, it can be turned on, but only as far as turning on the LED and fan inside the CPU. the monitor is dark, it's like it doesn't detect any computer (because the monitor's LED is blinking). LED light on my keyboard and mouse won't turn on, so I guess the Windows isn't loading when this happen(since the speaker is on, it should've played a login music if the windows was loaded)

the LED light and fan inside the CPU looks normal and sounds normal as usual. When in rare occasion I managed to turned it on, a light shake (like accidently kicking the CPU case) will makes the display goes off, as if it doesn't detect any computer again(I have to hard reset the CPU when this occurs)

any idea which component inside my computer is broken? any help is really appreciated

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Hello reny410,

 

Have you checked that the computer to display video cable is securely connected both ends, only finger tighten the plastic retaining screws (often blue in colour).

 

Please provide information about your computer, this includes is it a custom build or brand name such as Dell or HP, if it is a brand name provide the model name or series number (not serial) if a custom build post the brand and model name or number for the MB, amount of Ram, add on video card if one is used and the PSU (power supply unit) providing these details will enable us to better assist you.

[phillpower2]

Hello reny410,

 

Have you checked that the computer to display video cable is securely connected both ends, only finger tighten the plastic retaining screws (often blue in colour).

 

Please provide information about your computer, this includes is it a custom build or brand name such as Dell or HP, if it is a brand name provide the model name or series number (not serial) if a custom build post the brand and model name or number for the MB, amount of Ram, add on video card if one is used and the PSU (power supply unit) providing these details will enable us to better assist you.

[reny410]

hi there phillpower, thanks for replying . yes, the monitor cable is secured on both ends. I don't think that's the problem though, because when the problem occurs, the LED on keyboard and mouse won't turn on, too. Correct me if I'm wrong though.

as for my computer specification(it's custom build btw):
Intel core 2 quad q9550
ATI RADEON 7970
4GB of RAM
ASUS P5Q SE 2 motherboard
1000W PSU. forgot the brand name :/

everything beside the VGA is quite old, but I never had problem with this before.

so in summary, the problem is:
-PC fails to boot
-When it fails, the fan and LED inside computer case turn on like usual
-when it fails, the monitor won't display anything
-When it fails, I think it doesn't log in to Windows, because music won't play. so I doubt it's just the monitor
-when it fails, mouse and keyboard's LED won't turn on, as if there's no electricity there
-sometimes when it tries to boot, it get completely turned off(the LED inside CPU goes off, and then it tries to boot again, and fail, but LED inside is on)
-in rare case the boot is succeeded, a light shake on the case will makes everything turned off, except LED and fan inside CPU, which runs as if nothing happens

Edited by reny410, 18 October 2014 - 05:36 AM.

[phillpower2]

PSU brand and model name or number if you will please.

 

This does sound like a power problem btw, see my canned text below;

 

As a PSU puts out various voltages +3.3V, +5V and +12V it may appear that the PSU is working correctly but it is not, any significant drop of any output can prevent the system from booting up, the other scenario is a significant increase in the output which can be worse as it can fry one or more major components such as the MB, CPU, Ram, add on video card etc.

 

[reny410]

hi again, thanks for quick reply
I just added PSU in my post, it's a 1000W PSU, unfortunately I forgot the brand name
I've been thinking PSU too . if the problem in your post occur(when PSU fails to give correct output to the system), is it normal that the computer doesn't give POST beep after it fails to boot?

[phillpower2]

A 1000W quality brand PSU such as Antec or Corsair is less likely to fail but the same cannot be said for cheap generic imports, take off the side of the case and write down the PSU details that can be found on a sticker like the example below;

 

If a computer that normally emits a single beep when the power on self test (POST) has completed does not beep then one of the following is bad and commonly in the following order: PSU, Ram, video chip/add on video card, MB and then CPU, a bad keyboard can also cause POST to fail but not as often as the other hardware.

 

You are welcome btw 

[reny410]

hi, I just saw it and apparantly the brand is Cooler Master. How's that?

yes, my PC doesn't beep at all when I tried to boot it up. only LED's and noise of fan.
How do I diagnose which part is broken then? I also thought of motherboard, because sometimes after I replug the cables inside the case, the computer can boot like normal, maybe loose socket on motherboard or something, but I don't know if this is the correct way to diagnose things

[phillpower2]

Cooler Master are not the best but they are also not the worst, we do need to know the model name or number so that we can do some research to see how old it is likely to be, what the failure rate is and how many +12V rails it has.

 

Does your computer normally beep once when it boots up successfully?

 

As post in my reply #4

As a PSU puts out various voltages +3.3V, +5V and +12V it may appear that the PSU is working correctly but it is not, any significant drop of any output can prevent the system from booting up, 

 

 

LEDs and fans are fed off a different rail on the PSU than the CPU and add on video card are and so it only shows that the PSU is powering some hardware.

 

Are both the 24-pin ATX Power connector and the 4-pin ATX 12V Power connector both securely connected to the MB.

 

You have 4GB of Ram, is that 1 X 4GB stick or 2 X 2GB sticks.

 

I will suggest some troubleshooting steps once you have answered the above questions.

[reny410]

hi, I just opened the case and took photo of the PSU. it's in the attachment
my RAM is 2x2GB which makes it 4 GB

as for ATX power connector, I'm not sure, there's so many cables inside and I didn't build it myself, so I don't really know which cable is which. Can you tell me how does the cable look like?
edited: nevermind, I googled those cables and took a look, and yes, both cables is well plugged in. My PC still can't boot though.

Edited by reny410, 19 October 2014 - 09:38 AM.

[phillpower2]

Thanks for the update, you did miss one answer for us though and it is important that you answer;

Does your computer normally beep once when it boots up successfully?

 

 

Your PSU is potentially over seven years old so don`t be too surprised if it has gone bad, they only had a 5 year warranty btw so even if it is not the cause of the issue you should consider replacing it sooner rather than later, JonnyGURU tested the PSU back in 2007, details here

 

I put an attachment together showing the types of power connectors and have included it in case it helps anyone else that may read your thread;

 

 

[reny410]

ah, sorry about that.
Yes, my PC always beep once when it doesn't fail to boot. However now it doesn't beep at all.
any idea?

[phillpower2]

Disconnect all power connections from the computer, ground yourself by touching a bare metal part of the case or the PSU.

 

Remove both sticks of Ram, restart the computer, let us know if you hear any error beeps.