I have a dell inspiron 8600 does nothing after booting

this may help. just watch the video and folow the directions. good luck.

Lots of fans are variable speed. Meaning they spin faster when the computer is hot and slow down when not. It's most likely spinning down. If the fan was bad the computer will either shutdown or generate an error during BIOS and halt the boot process.

I would take the hard drive to a computer repair shop and let them scan the HDD and remove the infections. They can also repair the windows installation files so it will boot back up. Either way, you do not have to change out the memory unless you want to install more.

RUN CHECK DISK AND IF IT STILL WONT BOOT RESTART AND BEFOR THE WINDOWS LOGO COMES ON PRESS F8 AND CHECK START IN SAFE MODE THEN RUN CHECK DISK

shut down the laptop.
then, disconnect the laptop power, and battery.
remove the harddrive, then connect the harddrive firmly back into place.
reconnect power/battery and boot.

I assume you have already tried the Dell site & searched (using eg google) for 'Inspiron 8600 BIOS reset' so I'll not bother repeating your efforts.

Since you posted here, I can only assume you have been unable to find any information about special power-on key combinations or any small holes underneath (where a paperclip can be used to reset the BIOS) ... in which case your only option is to dismantle the laptop, locate the BIOS battery and remove it for 30 seconds or so.

To find out how to dismantle the laptop, search (google) for 'Inspiron 8600 BIOS Battery replacement' ....

Do you have any CD’s that came with your laptop? If so, look for one that has “Diagnostics and utilities” listed under the “Contents”. To boot from that CD disk, power on your laptop and tap the <F12> key to bring you to the “One time boot menu”. Insert the CD and then select CD/DVD drive and hit <Enter> key. You can also boot from the Windows reinstallation disk. If the computer boots from either CD, then your Operating System is corrupted and needs to be reloaded.

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Put the Dell CD in the drive bay. Turn on the computer and start pressing <F12> key. It should say "Preparing one-tome boot" When the screen shows a selection menu for the boot device, use the arrow keys to select the CD and press <Enter> key. That should run the Dell CD. Follow the onscreen prompts to run diagnostics checks

Start by cleaning the fan and heat sink. Dirt or dust build up can cause them not to work as efficiently as they should. If cleaning doesn't fix it, you might consider replacing the fan and heat sink or purchasing a cooling pad.

Unless you can see the little safe mode text in all 4 corners then it sounds like the computer IS in regular windows, but the video card drivers are gone. Try re-installing the video card drivers from Dell for that particular video card (there are several possibilities) and see if that helps. It is possible the video card is going bad, but usually re-installing the video drivers works.
This could be a sign of other problems too- start with the video drivers and see if that helps. If it does not- I'm guessing the operating system is corrupt, virused, or the video card is going bad.