Recently we've been getting a lot of questions from people who basically have the same problem - they've assembled a PC but it won't start up correctly!
There is a standard troubleshooting procedure for that scenario which everyone should follow, and I'll describe it to you in a moment. But first let me address a few common issues for people whose older PC won't start any more:
* Does it 'hang' when it's loading Windows or when it reaches the desktop?
If so your problem is most likely a software one and NOT a hardware problem. You should, of course, check that all the cooling fans are working (especially the ones on the processor and the video card) in case overheating is a problem. If you have two or more sticks of RAM which are from different manufacturers you could try using them one at a time in case a RAM mismatch is causing the problem. But other than that the only real way to see if it's a software or a hardware problem is to try running it with a fresh, clean installation of Windows.
Go buy a second hard drive. Extra storage space is always worth having and they're quite inexpensive. Swap your current drive out, put the new one in, and load Windows onto it. If all runs fine you know for certain that the problem is in your original Windows installation. If not you've got a second hard drive to use once you track down the hardware problem and fix it!
* Have you recently changed internal hardware items?
Added RAM? Changed a display card? Added or changed a drive? Whatever the internal change has been, if the machine won't start afterwards you've got clues to where the problem lies. Remove the recently added device or component and try again. If it still won't start have a good look inside to ensure you haven't dislodged or damaged some other component while you were working in there. Make sure everything is firmly in place.
* Have you reset CMOS?
No, setting it to default in BIOS Setup isn't good enough. When you make changes to the hardware of a PC you need to physically reset the CMOS memory, either by 'shorting' a jumper on the mainboard or by removing the CMOS battery and waiting several minutes at least before replacing it. A vast number of instances where machines won't start up are simply the result of changes made without resetting CMOS afterwards.
* Did you ensure that the power was switched off at the mains before working inside the PC?
Shutting down Windows isn't good enough. Modern ATX motherboards still have power running through them after Windows has been shut down! You must either switch off at the wall outlet or remove the power cord before opening it up to perform internal work. Damage to components can ensue if you make hardware changes when the motherboard is still receiving power.
Now, to the original point of this post.
* Does your newly assembled PC refuse to POST?
Even without a hard drive fitted, your machine should run the Power On Self Test. If it doesn't, then it is either incorrectly assembled or it contains a faulty component. You should be getting the memory check, the device detection information, and perhaps an 'Operating System not found" message.
Unfortunately, although PCs are quite easy to assemble, putting the whole thing together before trying it to see if it works is far from the ideal approach. If the entire PC is fully assembled, tracking down the reason for the failure can become a nightmare. The 'bare bones' approach is far better when assembling, and far better when troubleshooting. If your system is already fully assembled, go back several steps and try again.
The 'bare bones' PC contains only the following components:
- Processor heatsink/fan unit, connected to power
- A video card if there is no onboard video available
- One RAM module (unless the RAM is of a type which requires installing in pairs. 'Dual channel' RAM is NOT such a type!)
- The front panel connectors for Power Switch, Power LED and case speaker attached to the motherboard
- The ATX connector connected and supplying power to the motherboard. - The P4 power connector attached also if required. A molex connector attached to the display card if required.
That's it. Attach monitor and keyboard and see if it'll POST. Reset CMOS and try again if it doesn't. If you are building a new system stop at this point and try it out. If you're troubleshooting a fully assembled PC strip it back to this point and try!
If the PC won't POST in this configuration you need to determine why before proceeding:
*check power switch and LED connectors. If they are reversed the system won't start
* check that the processor is correctly fitted
* try a different RAM module
* ensure that the display card is correcxtly seated.
* get a technician to check it over if you can't locate the cause
Once the 'bare bones' system is operational, add other components one by one. Try starting the machine after every addition to check that it will still POST. This is the ONLY procedure by which you can adequately and effectively troubleshoot where a hardware problem lies.
'Other components' includes additional RAM modules, add in cards, drives, etc etc etc....
If your are troubleshooting a system which has already had Windows installed to a hard drive, add that drive last so that the system doesn't continually try to boot into Windows.
If you strike problems and need to post a new thread about your problem, include the following information:
* Identification details (make and model) of all components
* Full details of any onscreen error messages
* Full description of any BIOS 'beep' codes emitted through the internal speaker.
Cheers, and good luck with it.