Well 3x720p=3 x 720 x 1280 = 2,764,800 pixels
1 x 1080p = 1 x 1920 x 1080 = 2,073,600 pixels
So your pumping about 25% more pixels, so look up 250x reviews and see if it can do 1080p graphics in the games you want to play at high, then figure about about 25% less FPS give or take for more pixels, then take off a few more percentage for having to drive and sync 3 displays vs 1, and see if that FPS are acceptable.
Short answer, probably not really, the 250x is a entry level card.