Interesting... 2 MS docs from the same version of BOL that state different things...
Steve's reference for the question...
Another with a differing opinion. Doesn't change the answer to this question, but perhaps if we were discussing Std Ed it might. Just odd to see the variations...
50 instances on a stand-alone server for all SQL Server editions except for Workgroup. Workgroup supports a maximum of 16 instances per computer.
SQL Server supports 25 instances on a failover cluster.
To help us help you read this
For better help with performance problems please read this