You Visa status might be in risk based on the number of online courses you take in the Masters degree at US University while you are on F1 Visa. This Article talks consequences of attending more than one Online course in a semester or quarter while you are a student on F1 Visa in USA. Recently one students contacted me whose OPT is rejected because of 2 online courses he attended in a semester. He is leaving to India after Rejection of OPT. So, though of writing this.

F1 Visa Violation: Online Courses

To comply with F1 Visa rules you need to meet certain conditions. Here is a list of F1 Visa rules you need to follow regarding the courses you need to take during masters study to maintain as a full time student status at the university. When you are not a full time student at the university, you are violating the F1 Visa conditions. Following conditions should meet for a full time student on F1 Visa.

1. Masters students in USA can take only one Online course in a semester. There are many unaccredited schools and some schools which don't follow F1 Visa rules. They give more than one online course to students. International Student Service Officers won't guide F1 Visa student properly about the rules. Stay away from Online Courses. It would always help immigration benefits in future.
2. 9 credits or 3 courses are the minimum requirement to enroll in a semester as a fulltime student at US University. If you take less number of courses than 3 during the semester, you are out of status which means you violated F1 Visa Rules. Last semester is excluded from this. You can attend 1 or 2 courses in last sem.
3. If you attend 3 class room courses, you can attend any number of online courses which are additional courses in the same semester. So, 4th, 5th or etc courses you can attend online.
4. In Summer, you don't need to attend any classes. If your wish to attend or not attend. Still you will be considered as full time student.
5. You can't drop courses as you wish. Dropped courses will be reported to DOS with SEVIS system.

If you don't follow these rules your CPT or OPT or H1B visa or Greencard may be rejected.