I don't think so. The most powerful low profile card in the world is HD 7850:http://www.afox-corp.com/en/products_details.asp?proid=209&typeid=46&id=46
That looks like a pretty long card. Tried to do a google image search of optiplex 745 and came
up with both a shorter tower type case and more old school "desktop" chassis that can
either go tower style or lay flat(thinner of the 2). Guessing you have the thinner one since
you ask about low profile where the tower only chassis looks capable of full height cards.
Normally you are restricted to a narrower card in a thinner chassis, unless of course maybe
you are willing to run your computer with the side/top panel off. Depends on fit at the back
of the case, though.