HELP - PC boots up for half a second only
 

Specs: (off the top of my head)
Motherboard: ASUS p5-LD2-VM
Intel pentium d processor
nVidia 7600GT video card
x2 1GB Kingston Ram
Windows XP x64


My computer has been working fine for the last few months without real serious complications.

I finished using it yesterday, shut it off through the start menu as usual, and left for NYE plans.

Came back today, tried to boot up the computer, the fan/HD would start up and beep but then turn off again immediately. I would then have to remove the power plug and replace it, then push power again for it to boot up then shut down immediately. The Green LED on the motherboard itself is on.

I've tried -
- reseating all the plugs
- booting up with one piece of ram to test it ( i have 1GB x2 )
- unplugging all unneccesary devices and keeping the critical ones (eg. gfx card, HDD, PSU etc )

Yet to no avail, i'm completely clueless now what to do.

Due to the fact that it starts up momentarily, it can't be the PSU can it?
So it should be the motherboard's problem?

Any suggestions before I send in the motherboard for warranty?
Any insight is appreciated!

sounds like a faulty PSU. Try replacing it and see what happens?

+1. Sounds like a faulty PSU to me as well. It might not have enough juice to power EVERYTHING. I had the same problem where my mobo and fans were running, but no hd. Your needs aren't crazy so you can probably find a good 350W psu for about 40 bucks.

Check for bulging capacitors on the motherboard, as well.

Sound like it to me too.
If it's other stuff, you should hear more than one normal beep sound.

Most likely PSU. If you want to try it easy first do the PSU. If you don't have a spare one/want to put money on a new one yet: pull EVERYTHING that is non essential to startup. Add back one piece at a time. When it stops booting, you either have your faulty hardware or hardware combination that is causing the problem.

But like others have reiterated, most likely the PSU. At least with ram/cpu you would get bios to post.

Hey guys, thanks for the input.

This current PSU has been working for the last year so I don't think it doesn't have enough power (unless the performance of the PSU decreases over time)?

Anyways, looks like the general consensus is to replace the PSU, fortunately I have a spare one sitting around but I just wanted to clarify and confirm before I have to do the tedious task of pulling everything off the PSU.

Will update.

My guess is that it's the motherboard. I've seen this symptom personally several times, and as far as I remember, it's because of the motherboard, not power supply.

However, the motherboard could be so finicky that another power supply MIGHT make it work temporarily, but after awhile it'll probably crap out again. Hell, even replacing the power cord temporarily fixed a machine that had this problem for me, but ultimately the bottom line was it was the motherboard that was the problem.

i've had one similar case where there was something wonky with the 'reset' button where it kept thinking it was being pressed.

I'll double check if the reset button is being pushed in.

Regarding the motherboard, i'll be contacting ASUS to see if I can get it replaced ( definitely hasn't been 3 years yet so the warranty should still be valid ).

Now regarding the PSU , i thought i'd be ok cause the one i had in my closet was 400w and is brand new. Plugged everything in until the last plug, the one that connects to the motherboard, and found out that its only 20 pin, whereas the motherboard requires a 24 pin plug ( which the old PSU had ).

Guess i'll have to go out and buy a PSU, damnit.

your best bet is to just bring it into a computer shop, if you're not familiar with computers.
AHAH 39.95 fee..

Get one of those accessories to test PSUs.

Follow TekDragon's advice first: unplug the power connectors from everything non-essential: all drives (HDD, optical, floppy, etc.), all "extra" fans, anything else that has power connections (other than video card). Remove any non-essential cards as well. See if it starts and runs... if so, then start by plugging in JUST the system drive. If it boots at that point, it's most likely your power supply.

They don't "lose power over time" but it's possible an internal component has failed that's causing it to either shut itself down under load, or to simply no longer be able to produce the needed output.

If those steps don't help, then the PSU probably isn't the cause of your problems, so you can save yourself running out and buying a new one.

I followed this and what i've realized is that there is one plug from the power supply to the motherboard that is causing the PC to not boot properly.

The PSU has two plugs in total that go into the motherboard directly, one is the 24pin , and there's a smaller 4pin plug. I've narrowed it down to the 4pin plug, when it's plugged in, the computer will not boot properly.

However, with the 4pin plug out, the computer fans will start up, but HDD/system drive will not start up, this is probably due to the fact the motherboard NEEDS this 4pin plug to be plugged in.

So i'm assuming a new PSU is required now. . .

i know i need to buy a new psu with the following reqs:

- 400w
- 24pin connector

anything else to look for?

Ok well i got a new 400w power supply, hooked it up. The only thing different withthis one from the previous PSU is that it has one less connector for an optical drive, no big deal

However, I'm pretty sure i've plugged everything in correctly yet the computer still doesn't want to cooperate.

Fans spin, lights are on for the motherboard, but it doesn't boot properly. I've connected it so that ONLY the system drive is hooked up and that still doesn't work.

sigh. .i guess i'll go grab one of my family member's pc's and follow how they hooked up their PSU in case i messed mine up.

Now that you went the psu route it may be the motherboard like someone else mentioned. Could also be a completely dead hd. Those are easy to check if you have another computer/hd. Good luck though with it and too bad it wasnt the psu thats usually the most common :(

Can you get into the BIOS?
Does it beep once (go through POST) then restart again?
When you start up, does it show all the hardware info (MB, BIOS, RAM, IDE, SATA) then it restarts?

Try booting with only one stick of RAM in a different slot (rather than DIMM1) and see if you are able to load Windows.
If you can then a RAM slot could be bad (bad MObo)

If you still can't boot in Windows, unplug the HD (put the RAM back in) and see if the system still goes into a reboot loop or not.
If it doesn't, then your HD could be dead.

Do you had another video card? You can try plugging in a video card you know that works. Or if you have onboard try that and disconnect the video card you have plugged in.

That's what I could think of for you to try. Sorry if i listed ideas that you have tried already :)

Your motherboard may be shorting out somewhere on your case. Have you tried to take out all the parts and run it on top of your motherboard box, totally out of the case?

I'm telling you, it's the motherboard.

I can't get into the BIOS, no beeps, HDD doesn't whirr, i'm pretty sure it's not the HDD because it hasn't had any symptoms of failing hard drive previously.

At this point, I guess I will have to send in my motherboard to get it warrantied, this is going to be a pain in the ass isn't it.

If you can't live without your PC for several weeks, go out and buy another motherboard that has the same CPU socket type.

You can do a repair installation of WinXP and you'll be back up and running with your system just like it is now.

After you get the warrantied motherboard back, you can save it as a spare, or sell it...

OH MY.

THIS IS FIXED.

so basically today i went to NCIX richmond, bought a motherboard, noted the " NO RETURNS, ONLY EXCHANGES FOR EXACT ITEM " so i knew i needed to get the right motherboard otherwise i'd get dicked.

The sales guy (IVAN) doesn't seem the most friendly at first. Anyways he directed me to the motherboard, bought it and brought it home after running a few errands.

Now with my new PSU in the case, i thought i should at least test one more time before i begin stripping my computer apart to replace the motherboard.

Turns out it was a piece of RAM that caused it not to boot properly. Son of a bitch.

Booked it straight to NCIX, had to look like a fool and ask to see what they can do with the motherboard (completely unopened and it's only been an hour or so). Ivan isn't exactly friendly, but he's definitely reasonable, allowed me to get store credit back, and suggested me a replacement RAM for my computer, walked out a happy customer.

Put everything together and here i am back on my PC. what a way to start 2009.

Thanks for all the help guys, i definitely learned a lot about the PC.

Good job on figuring it out. Yeah... forgot that RAM is a possibility too. I should have remembered... a couple months ago, I had a system that had 4 x 2GB RAM in it, and now I recall I went through the exact same thing. It had worked perfectly fine for months, but then all of a sudden it wouldn't turn on anymore. Like I said, from previous experience, it had always been the motherboard for me in a case like this, so I went out and bought a replacement motherboard and swapped it... except that didn't work either. After that, I finally started testing the other components and discovered one of the four sticks of RAM was causing the problem. I find that very weird though because I had always thought that RAM was one of those components that either worked or it didn't, not something that goes bad over time.

But anyways... sorry for not remembering that to help you out, but good on you for figuring that out on your own. :)

Good Job! I thought you've tried booting with one stick of memory. I guess you didn't try alternating the two pieces?

Whenever, i have a computer that won't boot properly. I always like testing the RAM. It's the easiest to test. Simple to remove and it will fit is MOST computers :)

But nonetheless, GOOD JOB on solving the problem.:thumbsup:

I did test the RAM by alternating it, however, this was with the old PSU.

After I got the new PSU, i didn't bother testing the RAM because i thought for sure it would be the PSU's problem instead of the RAM.

Guess it was both :S