If a desktop computer doesn't boot at all. ie. when you press the power button and nothing "powers up" - there's no fan sound, boot up screen, etc. What could the problem be? It's definitely a hardware issue but how do I check which component has failed? Also the motherboard's standby LED light is glowing, so does that mean there is nothing wrong with the motherboard, and most likely it's the power supply that's broken?
EDIT: Forgot to mention, I haven't open the computer case in ages and I checked all the cables and connections so it's unlikely it could be that problem.
if the power LED is on, it could be mobo, RAM, CPU, display. you have to test one by one.
If the power LED is powered on then yes it could be the motherboard, CPU, RAM and / or display. If there is not a LED light for power, then your power supply is fried. You need to replace it to get your computer working again, obviously.
Go to a computer store for more information, they're probably your best bet if you don't know what you are doing.
Well lets narrow down the possible faults here. It can't be your RAM or your GPU as these two will make a beeping noise if not functioning. It can't be your processor to as your desktop can't even boot up with power for the fans to run. I would say it is your PSU (power supply unit). You are referring to the LED inside the motherboard that is somewhat of an inidication if power is actually flowing through.
If I remember correctly, the motherboard LED will still light up even if the PSU is non functioning as voltage still passes through the PSU. But your PSU will no longer supply the power needed to boot up your comp. So if you have an old/spare PSU lying around, try changing it. IF it does display after changing the PSU but does not complete but stays on the bootup screen, then the PSU you are using is under powered.
While you are at it, remember to clean out all the built up dust in yor system for optimal functionning of the fans and handware.