would using gifted cash for co-op purchase ( 100% cash ) diminish my chances of being approved by co-op board ?

yes, it would decrease your chances but it wouldn't eliminate them. So much depends on other co-factors: are you a student or are you working? where is the gift coming from, and under what circumstances? what kind of post-purchase reserves are you carrying? what has your record as a tenant been? what do your taxes look like? etc.

I would recommend paying extra attention to the rest of the board application to build a solid package. I brought an all-cash buyer to a not-particularly high-falutin' building on the Upper West Side, and got him board approved ... but we did put together an application the size of a phone book.

If you want to ask more specific questions, you can email me at: ali [at] dgneary [dot] com

ali r.
DG Neary Realty