SQL Clustering Preferred Owners
I noticed that in the sql failover clustering under the possible owners none of the nodes has been checked, I have a two node cluster does that mean in the event of failover it will failover to any of the active nodes.


You only have two nodes. If there is a failover... there is only one node to fail to, so having preferred owners set is... kind of a wash. It doesn't get you anything, to be quite honest.


  Whats is the difference if both of the nodes are checked vs if both of the nodes are unchecked as possible owners. 


In a two node cluster there is no difference. There is only one other node to go to so it doesn't make much sense.

Now, assume you had an X node cluster where X is > 2 and you're still using SQL FCI's (Note: AGs work differently, don't check or uncheck these values).

Now, if you choose "Move service to best possible..." it'll go to a preferred first, additionally if there were a fail over it'd move to a preferred first as well. Since it's all about preference and not about actual possible owners, having a preference set is unlikely going to really change anything, in my honest opinion.

Some will argue about fail back, which I don't like to enable and requires there to be a cluster event for failback to occur anyway... so it's a wash.