Entity with >150 attributes: One table or many tables with relationships
First off, apply normalization to the table and make sure that it really is one table with 170 attributes and not several tables jammed together.  

Then decide whether your table will be sparsely populated and if so, decide whether storage space is a concern that warrants creating sub-tables to hold subsets of nullable columns.  

If you do decide to create sub-tables, remember to factor in the extra index space when calculating whether a sub-table saves storage or not.