CheckDB on Partitioned Table - Insufficient Memory in resource Pool default
Paul's explanation might answer your question , you can take a look here 
http://www.sqlskills.com/blogs/paul/checkdb-from-every-angle-why-would-checkdb-run-out-of-space/. I have copy pasted a snippet from his post related to your question:

There’s another reason that DBCC CHECKDB may stop with an out-of-space error.  DBCC CHECKDB has to validate the contents of the whole database. As such it needs to store info about things it has seen at one point during database scanning so that it can match that info against things it sees at later points during database scanning. These bits of info are stored in an in-memory worktable. In many cases though, the amount of info being stored exceeds the available memory and the worktable needs to spill over to tempdb. (For example, running DBCC CHECKDB against a 1TB database on a machine with 16GB of memory – the amount of info that DBCC CHECKDB needs to store the intermediate pieces of info will likely exceed the memory available to SQL Server). So – if tempdb isn’t big enough to store the worktable, it has to grow. If it can’t grow, then DBCC CHECKDB will fail because it needs the worktable to operate.