You cannot set the number of worker threads or the number of I/O completion threads to a number smaller than the number of processors in the computer.
If the common language runtime is hosted, for example by IIS or SQL Server, the host can limit or prevent changes to the thread pool size.
Use caution when changing the maximum number of threads in the thread pool. While your code might benefit, the changes might have an adverse effect on code libraries you use.
Setting the thread pool size too large can cause performance problems. If too many threads are executing at the same time, the task switching overhead becomes a significant factor.
Windows Mobile for Pocket PC,
Windows Mobile for Smartphone,
Windows CE Platform Note:
The maximum value that can be set is 1000.