Ok i tried to upgrade my Mac Pro 4.1 to a 5.1 by using the firmware hack and CPU upgrade. Dual Xeon E5520 2.26 Ghz to Dual Xeon X5650 2.66 Ghz 6GB DDR3 1066Mhz NVIDIA GT 120 i did everything this guy did: https://www.youtube.com/watch?v=YAdgT-hJuXU Now. Everything is installed. I power the device on then I can see 1 red LED blinking for a extremely short time as soon as I power it on. The machine works but I dont hear a startup chime and im stuck with a blackscreen. This happens If I dont really turn the "screws" hard. If i turn it hard I can see a constant Red LED from the same spot its not blinking, it stays on and doesnt do anything and also the Fan gets on max speed I searched so much and was so careful, please help me!