revving fan/disk drive...now wont restart

so for the past few months, my dell dimension e510 has been suddenly restarting for no discernible reason...and it seemed to be fine once it restarted. then 20 minutes later, it might do the same thing again. or sometimes it wouldn't. one night it went black and tried to restart, and instead started making a revving sound like a car revving its engine again and again. i couldn't tell if it was the disk drive or the fan. i panicked and unplugged it, which stopped the noise. the next day, everything was fine. i backed up some of the most important data, but then everything seemed to be fine for about 3 weeks. however, last night the same thing happened with the fan/disk drive revving, and i unplugged as soon as i could. but this time, it won't restart. i turn on the machine and only get the orange "idle" light, and the monitor reads "no signal." i've checked for lose connections, tried different power outlets, unplugged all unnecessary peripherals. nothing changes. i have NO idea what to do...any ideas? thanks so much in advance

 

Sounds like a heat issue or a failing power supply.

I presume this is a desktop? Trying cleaning all the dust out. Get it all off the motherboard and cpu. Clean vents, clean blades on your fans(don't let them spin, hold with pencil) make sure all fans are working.
Make sure power supply fan is running.

Hill

 

Could the revving be coming from the CD/DVD drive? These can be quite loud ocassionally and may cause vibrations in the panels of the case. They can spin up unexpectedly, example, if you open My Computer when there is a disk in the drive.

Try not to pull the power lead out. That can damage the disks of a harddrive (upset voltages, etc). If you press the power button there may be a 4 second delay before it shuts down. You should be able to change this to instant shutdown using Power Options in Control Panel.

If you cannot get it to start, you may need to "clear the CMOS ". The method should be in the computer's manual. A method is to remove the CMOS battery from the motherboard for, say, 30 minutes.

There may be damage to the drive/s. You can disconnect the cables to the drives. It should start up, but give an error message that there is no disk or operating system. Try reconnecting the drives one at a time.

Matt