XPS 8960, whirring / 'boot-up' sound on repeat when CPU is not in use

it is the cpu fan speeding up and down.  you may think it is sleeping but there are a lot of background operation it does when you are not aware including updating etc.  Its sleep definition is not interacting with user demanded apps but its backside is not all dead.  lots of loading unloading like a supermarket at 12 midnight apparently no one inside but its back loading dock getting new supplies unloaded and set up for a smooth operation next time you work on it.

XPS 8960 Sleep doesn't behave the way it does on other PCs. A number of threads in XPS forum about similar XPS 8960 Sleep issues. So search for them...

If you want to see if you can identify an app or background process that may be waking the PC, open a CMD prompt window, Run as Administrator. At the prompt, type in powercfg -lastwake and press Enter. What does it say?

Some users find that using Hibernation instead of Sleep can be a work-around. 

We see that the issue you reported has not been resolved. I am a technical supervisor from the Dell social media support team. Please reply to this message when you are available so we may continue working toward a resolution.

@DELL-Cares​ I'd like help with this issue.

@RoHe​ it says:

Wake History Count - 1

Wake History [0]

Wake Source Count - 0

@JBadda​  Unfortunately, that's not helpful. So you'll have to work with Dell Tech Support for a solution