There was defiintely a different cooling system for 125W cpus but I do not know the part numbers.  [NAME]-Chris M would have more information for 3640 and 3650. Either way there is no XMP on a precision model.  
Hi,i have just acquired a Dell T3640 precision workstation with a core i5-10500 processor. Can the Dell T3640 support GEN 11 processors? (i know what the standard support document says) - specifically i am looking at the W-13xx series of processors but cannot find out if it is supported. regards and thanks in advance!
Dell T3640 support for GEN11 processors?