My pc work by itself without pressing power button
hey guys......iam facing a weired problem with my pc....last night i was working on my pc and turned it of normaly with out any problem...but at the next morning when i pluged the cable power to the outlet the pc started without pressing the power button and there was nothing showing in the monitor (no post..no bios...nothing)....and when i tried to press the power button for 5 seconds to turn the pc off it doesnot turn off....and the weirdest thing is that i removed the power indicator,hdd activity indicator and reset switch indicator from the internal connectors in my motherboard and the pc is still turning on by itself when i plugin the powewr cable to the outlet....i removed the ram and the VGA and tried to clean them...i removed the cmos battery and put it back again...the cpu fan is working fine and there is acooler above the cpu...plz guys help me
so, it turns on, but you get no display on the monitor? sounds like a PSU issue. Also, do you have on board video? if so, remove the gfx card and try that. Faulty pci cards can cause the issue you are having. have any other cards> sound card etc? Go to a bare minimum config. then put it back on the PSU and lastly motherboard.
thanks for replying....as i said i have external vga card ..i removed it and cleaned it then i put it again...i don't have any additional cards in my pc...i dont think vga have any relation with the power problem iam facing.... also i dont understand your phraze(go to a bare minimum config)..can u explain it plz
The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.
I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.
Breadboard - that will help isolate any kind of case problem you might have.
Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.
Make sure you plug the CPU power cable in. The system will not boot without it.
I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.
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.
A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.
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, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.
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.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.
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.
thanks jsc.....but you are far from what iam talking about...well,the only thing i can tell u now that the pc is giving me a short beep while booting which means every thing is ok as i think......this self power turning on is driving me crazy....can anybody tell me the cycle of the power in the pc when i press the power button, it may help in solving this problem
Try unplugging the case wires and using buttons on motherboard if it has them. This was the case for my system. Seems I kept using the same crappy case with the same crappy wires and it wasn't allowing the computer to start properly and kept resetting and resetting over and over and over just because of faulty power wires in the crappy case that I had