trying to figures why my device fan constantly spinning and heat-up even though there is no heavy application that was running. Was also checked the task manager to ensure cpu, memory, disk are in low usage.
eventually make some research to use the support assist tools from dell and been stuck in this “scan hardware” for almost an hour at 90% rate.
Yeah, same for me on my Alienware Area 51m, except it stops at about 91%. I think this started happening after a recent update to SupportAssist. I suspect there may be an issue with the update, but that's just my opinion. If you run SupportAssist at boot time by pressing F12 at the BIOS screen and select SupportAssist Recovery, you can run the hardware scan in there and all should be okay. It was for me.
About the fan noise... are your fan vents clean. Fluff and dust can build up and cause the fan issue.