Both of you: That "loud whirring sound" you're hearing is the CPU fan going full speed all of a sudden.
Many of the fans inside a case nowadays have the ability to adjust their speed based on a signal from the motherboard (BIOS/firmware) and/or the temperature inside the case (via a thermistor.) BUT, the DEFAULT state for such fans is "FULL ON" (which makes a LOT of sense when you think about it!)
So the only reason that you hear that sound is because the system has gone into startup again (as a result of the just-prior crash), and the CPU fan goes back to FULL ON until the system gets control from the BIOS and sends it the "CALM DOWN!" signal/info.
In your case, Spidey, when you continue to hear the loud whirring sound upon startup - for longer than startup would/should take - it's because your system is FAILING to take over from the BIOS/firmware. I.e. It's "jammed up" during the hardware part of startup.
While this is helpful, it, unfortunately is not possible to diagnose from a distance: It requires hands-on diagnostics of individual components (i.e. yank them out and test them independently) - including the mobo itself (as was the problem in Jane's case), and special (low-level) diagnostic SW and even diagnostic hardware.
(learn about POST devices.)P.S. POST devices are getting more commonplace, actually! My new mobo has one
* - with a two-hex-digit LED display - built right on it! It told me that I was having problems with my memory the first time I tried to boot it up, and I was able to correct the problem right away as a result! No guesswork or trial-and-error stuff! Kewl!
* If you look in the bottom-right portion of my mobo in the first pic of this post (if you view the image separately you can zoom in and see...) you can see the hex digit LED display. It's the little gray block slightly hidden by the colorful bunch of wires (front panel connections.)