If your computer is only able to successfully load Windows after re-starting several times, your PC is likely to be encountering one or more of the following problems:
If your computer is not beeping or beeping irregularly when it is starting up please see Problems with the Power On Self Test (POST).
Before you carry out any work on your computer make sure you protect your PC's delicate circuits from static electric charges on your body by properly grounding yourself. If you don't have a grounding strap at least ground your body by touching the metal part on the outside of your PC's case before touching the inside of your PC or any component, including the motherboard.
A bad, failing, or inadequate Power Supply Unit is often the cause of this issue. If the hard disk drive is not getting enough power during the first time the computer starts, it will be unable to spin the hard disk platters fast enough to start the computer. However, if you restart the computer two, three, or more times, because the platters are already spinning, it is able to get the drive up to speed and able to boot off the drive.
If you are encountering this problem after installing new hardware in the computer, it's also possible the Power Supply Unit in the computer is not supplying adequate power to the computer. For most computers we recommend you have at the very least a 400-watt power supply.
This issue can also be caused by a failing or bad hard disk drive. Similar to the last section, if there is a failure within the hard disk drive that is causing the disk platters to not spin up fast enough during the initial power up, you may also encounter this issue.
If after replacing the Power Supply Unit you continue to experience the same issue, it's likely that the hard disk drive is at fault and should be replaced.
Although not as likely as the above two causes (bad Power Supply Unit or Hard Drive), other hardware can potentially cause this issue to occur. For example:
Replace the IDE/EIDE or SATA interface cable connected from the motherboard to the hard disk drive. If the cable is defective it could cause various issues with your hard disk drive.
Finally, if the computer continues to exhibit the same issue after following all of the above steps, it's likely that the motherboard is defective and needs to be replaced.
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