Booting up with GPU

[goal778899]

Guys, i have an issue. I was in the midst of assembling an old system but whenever I insert a gpu into the motherboard. The system would not boot up. However if I remove the GPU and boot it using the on board VGA port, it will boot up. can you guys help me out with this issue? Thank you 
The system specs are : 
Intel pentium 4 3.2 ghz 
motherboard: ms-7254 
memory: 2x 1gb ddr2 memory 
Graphics card : powercolor hd5770 
PSU: ANDYSON 550w

[T-Aero]

You're using the GPU ports right?Because if not , the image will not appear on your monitor , and may there's why nothin appears,not because it doesn't boot up.