No dude.....
As far as i know ....nits just check your AIEEE performance and the minimum requirement in terms of boards is just a PASS in the brd xam..
Regarding placements though brds play an imp part but not the whole part. Your presence in an nit will to some extent overshadow ur performance in brds.And companies also consider ur performance in the institute...
As an example.....My friend got arnd 85 in XII.....in the end he was offered a salary more than that of another person who got 95.
So just chill and atleast do well in the institute..