If you've had this computer for a while now, I would open up the case and clear out and dust or debris that might have collected resulting in overheating your computer due to ineffective air flow from the fans. If that doesn't work, you can try these next steps:
1.Power off and unplug
2.Press/hold power button for ~15 sec
3.Open case and remove motherboard battery
4.Press/hold power button for ~30 sec
5.Reinstall battery (right-side-up!)*
6.See if it boots with only mouse, monitor and keyboard connected
If that doesn't work, you can check out the Dell support page that describes what your beeps and lights may be telling you as well as the troubleshooting for each step.
http://support.dell.com/support/systemsinfo/document.aspx?~file=/systems/inspd530/en/om/html/trouble.htm
If you have any further questions please ask
~Gadget~