Antonio you must use nvminer or ccminer-djm34-m7v7.
2015-01-20 17:37:31] GPU #3: GeForce GTX 750 Ti, 4544 kH/s
2015-01-20 17:37:31] accepted: 1361/1368 (99.49%), 22508 khash/s yay!!!
2015-01-20 17:37:49] GPU #1: GeForce GTX 750 Ti, 4402 kH/s
2015-01-20 17:37:49] accepted: 1362/1369 (99.49%), 22507 khash/s yay!!!
2015-01-20 17:37:49] GPU #0: GeForce GTX 750 Ti, 4427 kH/s
2015-01-20 17:37:49] accepted: 1363/1370 (99.49%), 22504 khash/s yay!!!
2015-01-20 17:37:50] GPU #2: GeForce GTX 750 Ti, 4426 kH/s
2015-01-20 17:37:50] accepted: 1364/1371 (99.49%), 22495 khash/s yay!!!
2015-01-20 17:37:55] GPU #2: GeForce GTX 750 Ti, 4351 kH/s
2015-01-20 17:37:55] accepted: 1365/1372 (99.49%), 22490 khash/s yay!!!
2015-01-20 17:38:01] GPU #4: GeForce GTX 750 Ti, 4349 kH/s
2015-01-20 17:38:01] accepted: 1366/1373 (99.49%), 22485 khash/s yay!!!
2015-01-20 17:38:07] GPU #4: GeForce GTX 750 Ti, 4426 kH/s
2015-01-20 17:38:07] accepted: 1367/1374 (99.49%), 22482 khash/s yay!!!
2015-01-20 17:38:07] GPU #2: GeForce GTX 750 Ti, 4495 kH/s
2015-01-20 17:38:08] accepted: 1368/1375 (99.49%), 22484 khash/s yay!!!
2015-01-20 17:38:14] GPU #1: GeForce GTX 750 Ti, 4364 kH/s