06-05-2019 07:18 AM
Welcome to the Community Forums.
Based on the description for each board part number:
90000107 LZ3 MB UMA 100M (Z580/Z585)
Compatible Models MTM 215124U 215128U
* this would be for older models that typically have preloaded Win 7
90000921 Mb(w8) Lz3 Uma 100M
Compatible Models MTM 59345242 59345254 59350984
* newer released variants of the Z580 with Win 8 preloads
I suggest to get what came originally with your machine checking it with parts lookup using your serial number.
I hope this helps answer your query.