Steve Jones - SSC Editor (1/22/2013)
Michael Valentine Jones (1/22/2013)
Generally speaking, you will not see much improvement from having multiple tempdb files, except under specific conditions that are fairly rare.This is good info, but slightly old. The current recommendation from Bob Ward, of MS and CSS, is one file per core for < 8 cores. Above that, use 8 files and monitor: http://social.msdn.microsoft.com/Forums/br/sqldatabaseengine/thread/bb1ddba4-253d-478c-ac58-0abb23775000
On that thread, Jonathan Kehayias says the following, which is just the point I was making:
"If you don't have tempdb contention on a PFS, GAM, or SGAM page, changing file count won't matter a single bit for the performance of the server, so it would be best to monitor for the contention first and then base your configuration on whether you have contention or not"