You got 1 PCI-e 16x slot, if you don't have anything in there, sure it will fit.
but will I be able to handle the card sence my mother board can only draw 35 watts?
I don't know where you got that information from, but it's totally wrong, and as I said earlier my friend, if you don't have anything in that slot, you can buy it! Good luck.
I get that but I don't want to drop 200 dollars on this card if it wont work I have seen multiple posts of people only going for lower end gpu's mentioning the mother board with the same dell optiplex 790 mt.