first of all thank u for ur respound
my hp model is HP Compaq dc5750
but i upgrade it with Ati radeon hd 5145 and 2giga ram
and it was work normal but when i remove vga and ram to clean my pc and put them again the windows can't start
i get the hp screen and give me one alert (beeb )and that is it ablank screen and did't open windows
i hope u will reply me soon
thank u