Computer won't boot and fans race - HP Compaq Pro 6305 Microtower Business Desktop PC - E3S34UT

OverheatingWhen the CPU overheats then it will shut down (i.e. thermaloverload) and won't boot up again until it has cooled down. If this is theproblem is not fixed then the CPU will eventually fail.
A faulty fan causes the problem or the fan and heat sink assembly are cloggedwith dust.
Check the CPU fan to see if it spins freely, if not replace the fan.
If the fan and heat sink is clogged with dust the remove the dust and make surethe vents are clear and dust free. Use a small brush and can of compressed airto do this.

There are 2 basic fans in Dell tower one for the power supply and the other for the Processor. If your computer is not booting then the Processor fan is most likely to be the culprit. What could be happening is that the Processor fan is no longer turning fast enough to cool the processor, so normal the processor when it over heats there is either protection to switch off the computer automatically or the computer won't boot. The best thing is to change the fan and make sure it is working properly but checking on the cables that they won't entangle on top of the fan to impede it's movement. You can easily damage your processor if the fan is not working properly.

This may be due to a CMOS mother board battery. I know that some tech or expert say that you can still boot without it but my experience is that if the CMOS battery is below 3.4 volts it may or may not post or boot. This battery is about the size of a quarter usually found at Walgreens or Walmart for about 3.00 dollars.

Hey Darrick, It seems that the fan is full of dust or gone bad. You can open the tower and use a compressed air can to clean out the fan. if cleaning it does not help call Dell sales and order a new heat sink fan.