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Dell Optiplex 745 Small Form Factor Troubleshooting

Released in 2006, these computers are highly sought after for their dependability.

Your computer refuses to turn on no matter how many times you press the power button.

The power switch on the power supply may be in the off position, or the computer could be completely unplugged. Check the back of the computer where the power cord plugs in to make sure the cord is securely in the power slot. Next, make sure the switch directly below the power cord slot is set to “On.” If the computer still does not turn on, it’s time to find out if the power supply is working correctly.

The power supply may be broken. Press the power button. If it begins blinking an amber light, it may be time to replace the power supply. See our power supply replacement guide here.

If the computer still refuses to turn on, there may be an issue with the motherboard. Inspect the motherboard for bad capacitors. Capacitors are the tall cylinders standing up on the board. If the top of any capacitor is domed or leaking fluid it needs to be replaced. Replacing capacitors is difficult and requires skill in soldering. Following are links to Youtube videos for anyone who is knowledgeable in soldering and would like to attempt to replace the capacitors.

Part 1: Replacing Capacitors Part 1

Part 2: Replacing Capacitors Part 2

The computer functions properly but DVD’s/CD’s are not being read.

If your computer seems to be working properly but your DVD's and CD's aren't playing, the problem could either be a bad disc or bad optical drive.

If you try the disc on other computers and it's still not being read, it’s a bad disc and there’s nothing wrong with the computer! However, if the disc isn’t the problem and can be read on other computers, the optical drive may need to be replaced by following the optical drive replacement guide found here.

Fatal blue screen and freezes can be due to faulty hardware. Following are a few tests you can do to check two pieces of hardware, RAM and hard drive, that commonly cause computer freeze ups and blue screen errors.

Faulty RAM is a common cause for the fatal blue screen. Download a free and easy-to-use program like MemTest86 to check for errors in your RAM. To be sure that the RAM is broken and not just improperly connected, follow the RAM replacement guide here to ensure it is properly inserted.

If you are sure the RAM is properly inserted but still get a blue screen, the RAM may be broken and needs to be replaced. Follow the RAM replacement guide here.

Corrupted files on the hard drive can cause freezes and the blue screen. Use this guide to check your hard drive for errors. If errors are found in the hard drive, then it may need to be replaced. Follow the hard drive replacement guide here.

If your computer is hot to the touch and/or powers off without pressing the power button, the fan may need to be cleaned or replaced.

There may be dust and debris keeping your fan from turning properly. Follow the fan replacement guide here to remove the fan and clear out any debris with compressed air.

If your computer still overheats, you may need to replace the fan unit entirely. See our fan replacement guide here.

If a moving part happens to break or become warped then it may make noise as it spins around. This part may need to be replaced.

If you place a disk in this drive and it starts to make noise (most likely a clicking noise), check to make sure the disk itself is not broken or warped in any way. If the noise persists, the optical drive may need to be replaced. Follow the optical drive replacement guide here.

If you hear clicking noises when the fan turns on (usually when the computer is warm and starts making a whirring noise), it may need to be replaced. Follow the fan replacement guide here to either remove and clean the fan or replace it.

If there are clicking noises coming from inside of the computer (while there is no disk in the CD drive and the fan is not running) when you boot it up, this is likely caused by a defective hard drive. It is recommended that you backup your hard drive immediately and follow the hard drive replacement guide here.

Computer tends to power off suddenly. if the computer is hot after shutting down, please refer to “computer is overheating” section.

It is common for a power supply to break after a power surge. If the power supply is at fault, do not attempt to open it. You may accidentally make contact with a lethal current. It is best to buy a whole new power supply if it’s the cause of the problem. Make sure all the power cables are properly connected to the outlets and to the computer. If all cables are connected. Test the outlets for power by connecting another device.

A faulty processor or a computer that lacks sufficient RAM may cause the computer to force shut down. To identify this problem, your computer would be running slow and crashing constantly. If you believe this is the problem, please refer to “computer is running very slow and/or crashing” section.

The computer will start to get very loud, the sides may get hot, and the computer may also turn off suddenly.

Press ctrl + alt + delete on your keyboard, then select task manager.

Under processes (which is selected by default), you will see a series of icons and names that correspond to applications (apps) that are running on your computer at the moment.

Under the column at the top marked “CPU,” Identify any process that is making your computer work too hard. These are denoted in red and will usually be near the top of the list provided. Right-click the name of this application, and select “end task.”


This same process can be done under the “startup” or “boot” tab to prevent having to do this every time you start the computer.

You may have a faulty fan. If the computer gets very hot, but not loud, this is the issue. First, make sure it is plugged in, and nothing is stuck inside keeping it from spinning. If you find your fan is broken, see fan replacement guide here for replacement instructions.

Programs or files are taking significant time to load.

Adding more RAM to Dell Optiplex can speed up the system. Avoid installing programs that aren't suitable for the system’s RAM because that can cause a slowdown too. You can add more RAM to your system but make sure they are the same model or type. more information can be found here and here.

Hard drives, much like any other components of the PC, tend to wear out. Installing a solid state drive (SSD) will allow the computer to run more smoothly. The reason why SSD is faster is because it relies on the processor rather than the hard drive. More info here.

Installing anti-malware/virus softwares can get rid of viruses. Another way to get rid of viruses, is to restore your system to a date before you got infected; by doing so, your PC will go back to normal speed. Restoring your system does not delete important files and documents.

When starting up the computer, everything is running fine, but the monitor is blank.

The monitor you are attempting to use may require that you use an HDMI cable. The computer does not naturally come with this. Look at the box that the monitor came in or the manual. The monitor must support a VGA connection, or you must have an adapter for this computer to work with your monitor.

The output for a monitor may be going through a bad graphics card. In the case of this computer, however, a replacement is not necessary because the motherboard has a graphics card built in.

This model offers a built-in graphics card, so removing should still allow you to see something other than prompts on the monitor. If the problem persists after removing the faulty graphics card, then the problem is in the motherboard. Unfortunately, these are very hard to fix, and it is recommended that you replace your motherboard entirely. For instructions on how to do this, see our (ADD URL) motherboard replacement guide here.

You go to your computer’s menu which displays personal files, hard drives, disk drives etc., but you cannot locate your files in that menu.

In the case that this hard drive has lost its formatting, you will need to reformat the hard drive. To reformat a hard drive, follow these steps:

Open windows disk management tool

Press windows+r on your keyboard to launch “run dialog” box

Type “diskmgmt.msc” and press enter

Identify among the list of drives the concerned hard drive. This will be easy because it’s details should read something like, “unknown”, “unallocated”, “not initialized”, and will display the amount of space the drive may hold or space remaining that is not yet formatted.

Right click on the disk’s name and select “initialize disk” in the drop down menu that appears.

Next is to select a partition style for your hard drive. Unless you have a good reason not to, select “GPT” (GUID Partition Table). This is the newer and more effective method for partitioning your hard drive. Then click “okay”

Once initialized you will find that you have been returned to the disk management window. Your disk should read “basic” and “online”, but still read “unallocated”.

Right click on the box the word “unallocated” is in and select in the drop down menu “new simple volume”.

Doing so launches a wizard setup for you to follow in order to format your disk.

Again, unless you have a good reason not to, use default settings and choose the full amount of the hard drive when deciding how much to partition, assigning a driver letter, and the file system.

Once the wizard is complete you should be returned to the disk management window where your disk should read “healthy(primary partition)” instead of “unallocated”. Now you have successfully formatted/reformatted, initialized, and added your hard drive to your computer.

In the event that your hard drive is corrupted, you may have to replace the hard drive. Locate manufacturer of hard drive and follow their protocol for corrupted hard drives.

One Comment

Dell optiplex 745 , after power off and power On while working, not working properly. Problem is when we are playing any video monitor screen goes to white and yellow screen, not showing video and desktop main screen also., What's the problem please suggest me.

srindra Drb - Reply

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