Thanks Mazzinia. When I searched the Dell site it states the 7820 is compatible with Xeon Silver 4210 [URL] Also, I guess when I compared both CPU’s it would give me a couple of more options on storage and speed. The rest of the  characteristics looked the same. What I wasn’t aware of (nor didn’t think of) was the MB and the possibility of there being different types. I’ll take stock and rethink now.  
Hi I'm having trouble with no POST after swapping out the Intel Bronze 3106 to the Silver 4210. Pretty sure the motherboard (O5WJN2) is compatible. But even when I reverted back to the Bronze I couldn't get a POST, even though it was working perfectly before.  I bought the Intel Xeon Silver 4210 from Dell direct, brand new a couple of weeks ago. Ram used for the Silver 4210 is Cricial 16GB DDR4-2400 UDIMM. Original Ram used for the Intel Bronze 3106 was DDR4 2666 RDIMM. Power supply is good and I changed the CMOS battery. But I keep getting the 1 Amber, 3 White blinking.   Appreciate any suggestions as it seems I've stuffed up somewehere. Thanks
CPU Upgrade no POST - Dell Precision from T7820 Intel Xeon Bronze 3106 to 
Silver 4210