I cannot get my computer to start up. I am trying

Most monitors will behave that way if they don't get a signal from the computer so there's nothing to display. A quick check of the monitor itself is to disconnect the signal cable from the computer and then turn the monitor on. Most monitors will display some kind of a message that there's no input and to check your cable connection. Then the power indicator changes color as the monitor blanks out.

You will probably find that your computer isn't starting up when you turn on the power. A common computer problem is that it will turn on when you press the power button, showing a power light and you'll hear the fans inside start running, but it never actually starts running. Then there's no video to the monitor and you see the trouble you described.

The monitor may still be bad. If everything seems to be starting normally and you hear the Windows startup sound through your speakers, but the display stays blank, try another monitor. If that one works, you'll need to have the bad one serviced or replace it. If the test monitor is also blank, the video circuitry in your computer has failed. If the video is built into the motherboard, you can install a plug-in video card as a replacement.

If the computer is turning on but never starts running, that can be a pain to figure out because several things can cause the trouble. The most frequent causes are a bad power supply or motherboard. Bad RAM or a defective drive or other device connected to the motherboard can also keep the board from starting up. The processor itself can fail, but that's not common. I start by removing everything except for the power supply, processor and fan to see if the motherboard is starting. If the motherboard doesn't give a "no memory" error (usually a long beep), you need a power supply or motherboard. Otherwise, the basic hardware is fine, and you can start replacing parts until the trouble comes back, and then you'll know what caused it.

Good luck, and thanks for using Fixya!

Power supply light on or flashesPerform the following steps, in order, until power is restored or it is determined that there is a hardware failure: CAUTION: This product contains components that are easily damaged by ElectroStatic Discharge (ESD). To reduce the chance of ESD damage, work over a non-carpeted floor, use a static dissipative work surface (like a conductive foam pad), and wear an ESD wrist strap that is connected to a grounded surface, like the metal frame of a PC.

1. Disconnect everything from the computer, including the power cord.
2. With the power cord disconnected , press the power button on the front of the computer for five seconds.Plug in the power cord and test to see if the computer can turn on. If not, continue using these steps.
   NOTE: If the power supply fan makes an inconsistent grinding sound or stops and starts erratically, replace the power supply
3. With the power cord removed, flip the red voltage selector switch to the opposite position. Wait about five seconds, and then switch the red voltage selector switch back to its original location. Ensure that the voltage selector switch is on the correct setting, 115V for North America.Performing this step ensures that the voltage switch is engaged and set correctly for your country/region. Figure 4: Voltage selector switchPlug in the power cord and test to see if the computer can turn on. If not, continue using these steps.
4. Plug a lamp into the same outlet to see if the wall outlet has power. Try the computer in a different outlet in order to eliminate the outlet as a possible source of the issue. Test both to see if the wall outlets have power.
5. Remove all extension cords, power strips, surge protectors and any converters that remove ground. Plug the power cable directly to the wall outlet. Test for power. If this fixes the issue, find the device that is causing the issue and do not use it.
   NOTE: If you find the device that was causing the problem was a surge protector, resetting a breaker or fuse on the surge protector may fix the issue.
6. Remove all attached devices except for keyboard, mouse, and monitor.
7. Remove any internal component that was recently added, such as video card, memory, CD, DVD, and hard drives. An added device may take more power than the power supply is rated for. If the problem goes away when the component is removed, the only option is to upgrade the power supply to power supply with a higher wattage rating.
8. Check the power switch:
   1. With the power cord disconnected, press the power button on the front of the PC. The button should release easily and not stick in the socket.
      • If the button sticks, it should be replaced or serviced.
      • If the power button does not stick and appears to be functioning, continue using these steps.
   2. With the power cord disconnected, remove the case or side panel.
   3. Follow the wires from the power button on the front of the computer to their connection on the motherboard.
   4. Look at the power switch cables connected to the motherboard. If the cable has become disconnected, connect the power switch cable connector to the connector on the motherboard. Figure 5: Power switch connector on Motherboard
   5. Replace the side panel, plug in the power cord and test to see if the computer can turn on. If not, continue using these steps.
9. Find the defective part:
   1. With the power cord disconnected, remove the case or side panel.
   2. Disconnect all power cable connectors from their connectors on the motherboard and from the back of internal devices (the back of drives). Make sure to label or remember where each cable connects for future reference. Figure 6: Example of common power connections
   3. Replace the side panel, plug in the power cord, and examine the light on the back of the power supply:
      • If the LED is on solid and is not flashing, the power supply is probably good and the problem is most likely caused by a defective component (processor, memory, PCI card) or a defective motherboard. Have the computer serviced, or remove the components and replace them, one at a time, to find and replace the defective component.
      • If the LED is still flashing (it should not flash with all connectors removed), plug the power cable into a different power outlet that is known to be good. If the LED still flashes, the power supply should be replaced.
      • If the LED light is now off, plug the power cable into a different power outlet that is known to be good. If the LED stays off, the power supply should be replaced.
      
      NOTE: If an electrical storm or power surge has recently occurred, then it is more likely that the power supply, the modem, or motherboard is damaged and requires replacement. If the power supply was damaged due to power outage or storm, this may not be covered under the "act of nature" policy in the warranty statement. Refer to the warranty statement that came with your computer for more information.

It could be a defective power supply, motherboard, memory, PCI card or video card, loose motherboard screws, or just dust. The first thing that I always test is the power supply. The way I test is to either put a known working power supply into the problem computer or remove that power supply and install it into another computer to test it. If the power supply is testing good then I start with individual hardware components. You will need to disconnect one component at a time then try and boot the computer. For example start by disconnecting the power then remove the cd-rom drive power/ide connectors then power the computer back up and try it. If it starts after removing a hardware component then that is the problem. When it comes to the video card(if it has one) you will need to either install it in another computer to test it or install a working one in the problem computer. Also remember to try and clean the board completely of dust. Dust can cause a motherboard to short. And verify all the motherboard screws that hold the board to the chassis are tight...these are used as a ground.

Power Supply Types

There are two basic types of power supplies. There are AT power supplies, which are older and in older computers, and ATX power supplies, which you will find in virtually every new computer you can buy.

There are two fundamental differences between AT and ATX power supplies. First, the switch mechanism is different. AT power supplies use a normal on-off switch, which directly turns the power supply on or off.

ATX power supplies use a momentary switch which does not directly control the power. Instead, the switch signals the motherboard, which performs one of three actions:

• If the computer is off, the power supply is turned on (which turns the computer on)
• If the computer is on, the computer goes into power-saving mode (standby)
• If the switch is held for more than 4 seconds, the power is cut and the computer turns off.

Because of this difference, ATX power supplies are better for projects that require the second power supply to turn on automatically when the computer is turned on.

The second difference is in the motherboard connector: AT power supplies provide two 6-pin connectors (figure 1), which are easy to insert backwards. The ATX connector is a single 20-pin connector that only plugs in one way (figure 2).

Figures 1 and 2: The difference between AT (left) and ATX (right) motherboard connectors.
Both power supplies provide two types connectors for plugging devices into. These connectors are called Molex connectors, and they come in two sizes (see figure 3 and 4). A power supply will generally have a few of each size.

Figures 3 and 4: Large (left) and small (right) Molex connectors.
There is no difference between the two sizes other than the size itself. Both sizes provide the same amount of power to whatever device is plugged into it (12V and 5V). The small Molex connectors are generally used only for floppy drives. Large Molex connectors power hard drives, CD/DVD drives, and many fans and lights as well.

Note: You can purchase large and small Y-adapters if you run out of Molex connectors. Be careful when using the Y-adapters however, because if your power supply does not have enough power for all the devices attached (especially true for older, lower-wattage supplies), you can damage it.

gordonmic403

your very brief statement about your computer sounds like a power supply problem. I would suggest testing and / or replacing your power supply first to see if this is the cause.

The fan is drawing too much current from the motherboard causing the power supply to go into protection mode. Try replacing the fan with a new one and see this this does not fix the start up problem. You should check out your power supply and see if it really delivers enough power to power all the devices in your computer. The power supply could have weaken due to overheating and aging. Try checking the voltages with a software device like speedfan or hardware monitor and see if the voltages are intermittant or out of specs. These programs can be downloaded free from their websites. Just google them to find the websites. If they are you should replace the power supply. Hope this helps you with your problem.

Make sure at the very least that the power cable is plugged into the wall (or a UPS) AND into the computer (and it is switched on).

Try power button, if nothing happens then...

Look inside the computer, make sure that you have wires running from the front part of the case (usually near the power button) to some pins on the motherboard...

If not then you need to figure out what wires are what and plug them onto the pins (use the motherboard manual to figure this out, or the internet; google your motherboard name + jumper settings)

Try power button again, if nothing then try another power supply.

Post back if you have any further problems.

It's a dreadful way to start a day - you press the power button on your computer and nothing happens. Do not fear because all may not be lost! Follow these simple steps to determine why your computer won't turn on.

Note: It is very important to troubleshoot any issue beginning with the most likely and easily testable problem so be sure to follow these steps in order.
Difficulty: Average
Time Required: Anywhere from 10 minutes to a few hours or more depending on why the computer won't turn on
Here's How:

As silly as it may sound, the number one reason why a computer won't turn on is because it wasn't turned on! Before starting a sometimes time consuming troubleshooting process, make sure you've turned on every power switch and power button associated with your computer:
Power button/switch on the front of the computer's case.
Power button/switch on the front and/or back of the monitor.
Power switch on the power supply on the back of the computer.
Power switch on the power strip or surge protector (if you have one).

Verify that the power supply voltage switch is correctly set. If the input voltage for the power supply does not match the correct setting for your country, your computer may not power on.

Check for loose computer and monitor power cable connections. A loose or unplugged power cable is one of the top reasons why a computer doesn't turn on.

Perform a "lamp test" to verify power is being provided. Your computer isn't going to turn on if it's not getting power so you need to make sure that the power source is working properly.

A damaged power supply could be preventing the computer from being properly powered.

Do a quick test of the power supply by holding your hand behind the power supply fan located at the rear of the case. If the power supply is working, you should feel air from within the case blowing against your hand. If not, you may need to replace the power supply.

Tip: Is the power light on the front of the computer's case on? If you've turned the power switch on but the light is off, this is another good indication that the power supply is the cause of this issue.

Over time, internal components and the cables that connect them can wiggle loose which can often times result in a computer unable to power on. Try reseating the following and then try to power on the computer again:
Reseat the internal cables
Reseat the memory modules
Reseat the video card
Reseat other expansion cards

Reseating the CPU may also be necessary but should only be attempted if the reseating of all other components is not successful. This is due to the fact that this process is a little more involved and can run a small risk of damage to the CPU. This isn't a big concern if you're careful, so don't worry!

Check for causes of electrical shorts in the computer case. This is often the cause of the problem when the computer powers on for a second or two but then powers off completely.

Most monitors have a small light next to the power button that can change between various colors. If the screen is blank, this light is your main source of information about the monitor.

If this light is not on at all, double-check the power switch and connections (Steps 1, 2 and 3) and also make sure the monitor cable is securely plugged in to the video card port on the back of the computer case. If the light is still off, replace the monitor. If it comes back on, try starting your computer again - a loose or unplugged monitor cable may have been the issue all along.

An amber or yellow power light simply means that the monitor is not receiving any information from the computer. In and of itself, this doesn't tell us much.

On the other hand, if the light is amber or yellow, the computer power light is on, and the hard drive is active (making familiar sounds and the hard drive activity light on the computer case is blinking), the computer is probably starting normally but the video card is not sending information to the monitor. Replace the video card.

Beep codes (see Step 11) usually sound when a video card has malfunctioned but this is not always the case.

Is your computer making a beeping sound? Sometimes a computer will turn on just enough to play a series of beeps from the speakers.

These beep codes play in particular sequences and represent a specific problem that your computer is having. Troubleshoot the beep code to figure out what it's saying and then service the computer as necessary.
Tips:

Still can't get your computer to turn on? Let a community of computer support enthusiasts help out! Post the details of your problem in the Focus on PC Support Forums.

There's a small battery on the circuit board that helps the computer keep track of the time when it's off, so the original problem may be a defective battery.

The power problem could be caused by several things. It will require some testing by an experienced computer technician to figure out exactly what's wrong, but a defective power supply module is the most likely cause.

Other possiblities include a defective graphics adapter on the motherboard...or dust buildup around the microprocessor, which can cause overheating,

Sounds like your board has some issues (might of even caused your power supply to fail) try unplugging all IDE devices, removing pci slotted cards and anything else plugged into the board so you are only left with the Motherboard, Processor and Memory. Try to start the board now to see if one of your devices was causing the problem. If the board now comes on, try installing the devices back one by one to see which one is causing the problem. If that still doesn't work, try to further test your possible to see if they are working correctly. If all that fails, your board is probably the cause and needs to be replaced. Good Luck.