MAX worker thread in SQL server 2012/14/16
why max worker threads showing 2994 when i have 80 logical processors […]
  


It seems there is a documentation error when the item was copied over from MSDN to Docs. What you see in Dorr's post is correct and is applicable back to 2012 SP4 + latest CUs. I'll make the required documentation changes. The documentation has been updated.


  
  Coming back to that system health event status shows WARNING for below no […]
  


The reason you have a warning is because you have pendingTasks="1". This could indicate an issue with a scheduler and should be investigated.


  I see pending task count varying sometimes 2, 4 , 8 or even higher.


In the same Docs article that you linked, there is a query that can be used to track tasks and their status. It'd be interesting to see if it's only tasks on a specific scheduler, only login tasks, etc.

SELECT  s.session_id, r.command, r.status,  
   r.wait_type, r.scheduler_id, w.worker_address,  
   w.is_preemptive, w.state, t.task_state,  
   t.session_id, t.exec_context_id, t.request_id  
FROM sys.dm_exec_sessions AS s  
INNER JOIN sys.dm_exec_requests AS r  
   ON s.session_id = r.session_id  
INNER JOIN sys.dm_os_tasks AS t  
   ON r.task_address = t.task_address  
INNER JOIN sys.dm_os_workers AS w  
   ON t.worker_address = w.worker_address  
WHERE t.task_state = N'PENDING'