According to Intel the QX9650 is not compatable with your board. Prob. has to do with the watts the QX9650 is 130 watts , I would get a Q9550 95 watts. If you want to run the QX9650 , you would need a DX48BT2 , discontuined , but availble on ebay , $200.00 New.
I had the same problem, but after 3 days of madness I have found the solution...brace for it now...It's your OS!...yah your OS! For some strange reason MS Windows 7 Ultimate x64 & x32 will not finish installing using the "Intel DP43BF" Motherboard. I do not have a Windows 7 Home or Pro DVD to test, but I had my old "Vista Home Premium x64" threw it in & now I'm up & running like a champ!
Motherboard - Intel DP43BF
CPU - Intel Core2 Quad Q9300 2.5ghz
RAM - 4gb (2 x 2gb) Corsair XMS3 DDR3
GPU - 1gb nVidia GeForce 9500GT
HDD - 1tb Seagate Barracuda 7200 SATA
Optical - Sony CDR-RW/DVD Burner SATA
Power - 450watts
OS - Now! MS Windows Vista Home Premium...for now.
P.S. If anyone happens to get Windows 7 Home or Pro working on it please reply...Thank you & good luck all.