Does it make sense to buy a second GTX 770 4 gb?

Good evening friends. I have a monitor with a resolution of 1600x900, I want to take a 24 inch 1920x1080. I doubt that my video card will confidently pull this beauty, I think that 60 fps at maximum speed will remain a dream. So I'm thinking of taking another one exactly the same, for SLI. Do you think it's better for me to sell my card, throw in some money and get a more powerful one, or take a second one? And is there any point in changing also percents? Here is my config: MSi Z77A-G45 GAMING, Intel Core i5 3570K, GeForce GTX 770 4gb Gigabyte, 16gb RAM, Chieftec 750W, 1600x900. I will be glad to your advice.