my mains rank was 8731.my preferances are south side NITS,where i can get CS branch

Hey

You have low chance for getting cs but you can get other branches at NITs , you can get rough idea by checking previous year cutoffs of NIT, here I'm providing you with the previous year cutoffs of NIT on the following link where cutoffs are categorised branch wise
https://www.google.com/amp/s/engineering.careers360.com/articles/nits-cutoff-for-top-btech-branches

Hope this solves your query.
Good Luck!!