Upgraded an Inspiron 530 with a Vostro 400 MB, new Intel Core 2 Qaud Q8300 CPU. Boots and runs great,...chassis fan starts when power buttom is pushed , but omly runs for a second or two, then stops. Loaded "PC Wizard" and it shows each core temp at 35c to 39c, MB temp at around 40c. However another category shows the processor temps at 85c..WOW!! Readings also show chassis fan spinning at 1,753 rpm, but fan isn't. Tried new fan, not help, upgraded PSU from 300 watt to 400 watt, no help. Thought I downloaded lated BIOS, no help.
In your bios there is a section that deals with all this stuff ,,motherboard power something or other, you will know it when you see it,, check and see if things are turned on and,, not set tooooo looooow...
Laptops turn on the fan briefly when you power up in order for you to hear/see that the fan is working. Other than that it will only kick in again when the CPU temp reaches a threshold set by the bios.
Check the temp settings and lower them if you can, although being a Dell machine it's unlikely you will be able to change it as they lock the bios and give very few user options.
Thats one of the many downfalls of buying Dell, They're cheap for a reason.
Check on Dells support pages for a bios update which may fix this if it has been noted as a fault.
The only other thing I could suggest is downloading a 3rd party program to run in windows such as speedfan.
This will allow you to override the bios settings and set the fan as high or low as you want, on a timer or to lower the threshold temp.
PC wizard sounds like it is not reading correctly imo. If each core is under 50c then you should be fine, although ideally you would want 40-45c in a desktop, laptops by design always run hotter due to the limited airflow and smaller heatsinks.