I currently have a 4 core Xeon W-2125 cpu installed in a T5820. I would like to upgrade this to 10 core Xeon W-2155. I have done a lot of research and determined that it should be a straight swap - the motherboard supports all the W-21xx processors. However, my machine is running Windows 10pro and I have learned that it is probably only licensed for a 4 core processor, something Dell do at point of sale, although I can find nothing on my PC to say how many cores it is licensed for.

So my question is, if I install a W-2155, is it going to work? or do I need to contact Dell or Microsoft and pay a fee to upgrade the Windows 10 license? . If I paid the fee, would it involve having to reinstall the operating system?