Adding to the above

I have added additional .ndf(Size 4MB)  file to tempdb to release contention on .mdf (22GB Size)file of tempdb few days back.

It  looks like SQL server not using .ndf file for sorting operations  the size .ndf file still 4MB only.

Am I need  enable  any  additional  options  on SQL server  to use  .ndf file for sorting operations?