You probably could fit a GeForce GTX 750 Ti with a low profile bracket. The problem is you need a 300-400 watt power supply that is not available for your PC case. Nothing is available in the size for your case.
HP Desktop - 450-030d (ENERGY STAR)
Power Supply - Chasan 180W SFF E-STAR 6.0 Bronze
Part # 793073-001