This what I found here:
Assuming that you are refering to the Inspiron 580.
i3 and i5 processors are supported, i7 processors are not.
Intel Core i5 650 (3.2GHz/4MB cache)
Intel Core i3 550 (3.2GHz/4MB cache)
Intel Pentium Dual Core G6960 (2.93GHz/3MB cache)
Intel Core i5 760 (2.8GHz/8MB cache)
Intel Core i5 750, 45nm, 95w, processor (8MB Cache, 2.66GHz)
Prior to installing the processor, check that you have BIOS version A06, or higher installed, when Enhance CPU support was added
Anyway will look into your questions now.