Computer was working fine, then we moved it downstairs to where we set up a new desk, connected all the cords, plugged it in, pressed the power button and… nothing. It just won’t turn on. Another weird thing is that when I plugged it in, a little green light on the front and back started flashing. Then when we unplugged it, it kept flashing for a while. Not sure if that is relevant in any way, but I thought I should mention it.
So what could be wrong with my machine? Any ideas?
There’s probably a loose cord somewhere, either outside or inside the computer.
The green light probably means you’re getting power, so chances are you’re going to have to crack it open and take a look inside.
When you push the power button, what happens? Do you get any beeps, any noise at all? Or just nothing?
Maybe you jarred the video card or RAM loose? A motherboard without onboard video won’t boot up if no video card is present. Or maybe you decided to install a new motherboard and mounted it directly onto the metal case with no little plastic buffers and nearly fried the whole system. No…wait that was me…
We opened the box and checked all the connections and everything seems to be OK.
When I push the power button, nothing happens, no beeps, no noise.
Aunt Flow - I will tell my boyfriend to check the video card and RAM.
Thanks guys! Keep the diagnoses coming!
Is there a little rocker switch near the place where the power cord plugs in? - I almost didn’t want to mention this, because it sounds so patronising, but I have actually seen cases where the PSU switch on the back of the machine got accidentally knocked into the ‘off’ position and nobody thought to check it.
Also, try pressing and holding the power switch for about five seconds - it’s possible that the machine is in some kind of hibernation mode.
It sounds to me like a connection problem, too, but just to be sure, you should troubleshoot from the ground up. You can check that the power supply is working properly by unplugging it from all the other components and closing the “PWR-ON” line on the motherboard cable. Take the motherboard cable and use a paperclip to connect the green wire’s contact to any of the black wired contacts. If the power supply fan doesn’t begin spinning, you have a dead PSU. If it does, you can either assume it’s creating the right voltages, or check them with a multimeter.
This is good advice, but I think it needs a bit of fleshing out. Jurph is talking about the main power connector on the motherboard, which has a large number of different-coloured wires connecting it to the power supply unit - it looks like this - As Jurph says, you can push a bit of wire, such as an unfolded paperclip, down the hole, right alongside where the green wire enters and short this with a ground connection - same entry method, with any of the black wires, or indeed it should work if you just touch it against the metal of the case. Make sure you don’t poke it down the wrong hole though, or it could damage something.
If the computer had been sitting for a really long time on the floor, the odds are good that a fair bit of dust is inside the casing. ( No offense ! The dust is pulled in by the cooling fans ).
This makes pulling and re-seating the various cards a dicey proposition. If a card is even slightly NOT fully seated it can cause this kind of thing. But the dust, the dust. Clean it out very carefully, using a method of sucking or blowing the dust ( there have been threads on just this topic, or our experts here can chime in on which method they feel is safest ).
After the casing is fairly dust-free, pull and re-seat each card with the power off AND UNPLUGGED.
RAM chips are extremely hard to jar loose, as they are held in place with some degree of downwards force into their slots by the metal clamps on each end of each chip.
Betcha it starts up.
Best of luck,
Cartooniverse
And be sure to check the HDD and CD ribbons and power cords…
If it is very warm (in the room—most modern computers show the ambiant and CPU temperature at at start-up), these connections “like” to unseat themselms. Check the BIOS and the physical connections.
I have a fairly small apartment, and when I turn the computer on it is often (in the winter with windows open) less than 20C, after an hour the temperature may rise to 40C on the CPU, and once a month or so I have to reseat the cables both inside and out.
Also, try turning the case upside down - if you can hear anything rattling around loose inside, such as a screw or paperclip or something, that could have been shorting something to ground and preventing the machine from starting up.
Another simple possibility that you should check:
Many power supplies have a switch on the back to select between 120 volt (USA-Canada) and 240 volt (Europe). If you happened to bump that while moving the machine, and set it in 240 volt mode, but have it plugged into a 120 volt outlet, it won’t get enough power to operate. (That’s better than having it on 120 volt and plugging it into a 240 volt outlet – that would likely burn something out!)
These switches are often quite small, and hard to notice. And note that some computer power supplies don’t have them at all – they automatically adjust to the input voltage.
So you might check this on your machine.
Thanks everyone! We will try everything you mentioned tonight…
To Mangetout: yes we tried pressing and holding the power button, to no avail…
I find that resetting the CMOS battery sorts out a lot of problems with computers refusing to boot. How to do this varies from computer to computer but basically you need to unplug everything from the computer an take the case off.
Then locate the battery, it should look something like the one shown in this picture. Remove the battery and switch the jumper, in the picture you can see the red cap just next to the battery is on 2 of 3 pins, take the cap off and place it on the two to the right (so instead of being on pins 1 and 2 it is on 2 and 3). Wait about 30 seconds the put the jumper back onto 1 and 2 then put the battery back in and try booting it up.
I read about a person who rearranged the cubicle, and when everything was hooked up again, nothing worked. The person had plugged everything into the power strip, including the power strip itself! That doesn’t seem to be your problem.
Another one that threw me once was that I’d plugged the mouse and keyboard into each others’ sockets - it didn’t completely fail to respond on startup, but it didn’t even complete the POST.
