I wouldn't always say that.
For example, the downstairs PC doesn't always power on at the moment because the motherboard is going up shit creek... it has difficulty finding the USB Controllers and then hangs while launching, I also had a CPU that was on it's way out once that did the exact same thing, ... so diagnose further.
Can you get in to the BIOS? If so, check the temps after 10 mins on your motherboard & CPU.
Make sure your GPU fan is running and/or if any extra connectors for power are needed they are plugged in, this can cause the same sort of thing.
RAM Test your RAM.
Secondly, how old/new is your hard drive? Do you have a second rig you can put it in to and do a diagnostic on? Also, good idea to make sure SMART is enabled in the BIOS, this could tell you on a reboot if there is any obvious problems with your HD.
The very last thing you should do is test your power supply, if it is gone it is normally gone or you can hear it dying. Put your hand at the back, is it spewing out hot air? You normally only get "non-hot air" if you've got all your fans set the wrong way on your case, this could lead to it being a different problem. If you get warm air, you're fine, if you get really hot air, you've probably got a problem sitting idle in your BIOS. Test it with a voltmeter/ampmeter/all-in-one-tool thingy. Making sure the voltage is correct while in BIOS, as is the amps and watts (ie. my idle PC Power is 173 Watts @ 0.74a @ 242.9v - yours may vary but still shall be sort of similar, I'd be worried if your Voltage was way off
).
The reason you won't hear beeps is because some motherboards are dependent on you installing the speaker on the board, which 99% of the time I forget to do for boards that don't have one in-built D=
