Jameis Winston -- NCAA Investigating Point Shaving Allegations

The NCAA is actively investigating allegations Florida State QB Jameis Winston was involved in a point shaving scheme to help another college football player win a $5,000 bet ... TMZ Sports has learned.

We've learned ... the NCAA enforcement staff is actively trying to contact individuals it believes may know anything about the alleged plot.

The investigation stems from a report that Winston conspired with an old high school buddy -- UAB football player Chris Rabb -- to tank the 1st half of the FSU vs. Louisville game to help Rabb win a $5,000 bet.

As we previously reported, UAB has launched its own probe into the betting allegations.

We also know several of Winston's teammates are calling BS on the allegations -- saying Jameis "cares about winning too much."