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I turn on my pc then 2 seconds later it turns off.

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September 13, 2010 9:26:42 PM

I got home one day and my comp had the blue screen of death so i restarted it and I noticed an error message popped up the message said could not detect drive. So I figured one of my drives was going bad cuz I could hear 1 of them making a noise so I opened my case to take the power out of my drives to find out which one is making the noise. In the process of doing this my comp was powered up and i forgot it was and plugged one of the drives back in needles to say when I did this my comp powered down. I restarted it and the fans came on for 3 seconds later it shuts down I push the power button again nothing at all until I unplug the power cord then when i plug the cord back in and push start it comes on 3 seconds then turns itself off b4 post starts.
What I have done to troubleshoot it so far is.
pushed the start button several times to dissipate voltage.
checked the start button itself
changed out the PSU
resset all power connection from components
dissconnected and reconnected ram sticks
powerd up only the board with the 24 pinn connector by itself (when I did that the board beeped for 5 seconds then shuts down)
Im going to try to switch out MOBO CPU etc. but b4 I spend all that money any body have this problem before or suggestions of what might be messed up?

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September 13, 2010 9:40:03 PM

have you for giggles tried resetting your cmos? ( bios)
September 13, 2010 10:16:08 PM

Ya I reset the jumpers and took the battery out.
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September 13, 2010 11:47:42 PM

I would start by unplugging everything, then plugging back in the bare minimum (PSU, RAM, CPU fan) and see if you can get bios. Then add the boot HDD. Then add the other HDD, etc.
September 14, 2010 12:30:50 AM

An incorrectly mounted CPU fan will cause a computer to turn off almost immediately.
September 14, 2010 1:31:57 PM

I havent tried the cpu fan I will start with that. What are the signs of a cpu going bad?
September 14, 2010 2:07:59 PM

Yeh, you've not mentioned whether you've started from the bottom up, so to speak

Plug absolutely nothing into your pc, if you've got discrete gfx, remove that as well. Remove all hdd's, dont even plug in a screen. Have psu, cpu, mobo only.

Boot with no ram? - do you hear bios beeps? If not, mobo's probably dead. Does your PC stay on for more than 3 secs whilst beeping?
Hear beeps? - put in only one DIMM, does your pc appear to boot, does it stay on?

If the answer yes, your pc is probably ok so far
start adding parts one by one and see when it stops working
After putting in one DIMM and it stays on
add discrete gfx + screen - do you see anything? Your bios should post and say that it can't find anything to boot
If you get to here add your boot disk and I would expect everything to be ok.

Also what jsphdickens said - all this could be caused by a loose cpu heatsink, but if you've not tampered with that that's unlikely to "become" lose but is worth checking is fully seated. Crappier heatsinks can appear to be on but your cpu is basically shutting itself down to stop itself overheating, which usually takes only a few seconds.
September 14, 2010 3:41:13 PM

Thanks for the help everybody,
I have stripped it down to the board with the ram still in it, though i need to try it without the ram in it, but when i tried it stripped down to the board and just ram it beeped long for 5 sec's then shuts down where as with the drives and everything plugged in it doesnt beep just shuts down any idea what this means? I will try my comp without anything in it when i get off work.
a c 144 ) Power supply
September 15, 2010 3:47:39 PM

It could be practically anything - including the PSU. You could have partially fried it.

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:
http://www.cwc-group.com/casp.html

Make sure you plug the CPU power cable in.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU.

Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card. Silence or long single beeps indicate a problem with the memory.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
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