Normal
Found that in a 2014 post from Necere:"... if you want to use a V2 top panel, you need to use a V2 front. The side panels will work with either."source: https://hardforum.com/threads/ncase-m1-a-crowdfunded-mini-itx-case-updates-in-first-post.1717132/post-1040896936Which should imply a incompatibility between a V1 top panel and another version of the front panel.
Found that in a 2014 post from Necere:
"... if you want to use a V2 top panel, you need to use a V2 front. The side panels will work with either."
source: https://hardforum.com/threads/ncase-m1-a-crowdfunded-mini-itx-case-updates-in-first-post.1717132/post-1040896936
Which should imply a incompatibility between a V1 top panel and another version of the front panel.
