use same VGA cable to test 745 without XFX radeon hd 5450 1GB and verify onboard VGA gives normal video on same monitor.  then reinstall XFX radeon hd 5450 1GB and use same cable and same monitor to test.  make sure video cable connection is secure at both ends.

I tried many times but my GPU has VGA port missed and DVI is broken so i use HDMI to VGA converter

i can hear the internal speaker when i press F2 when i turn on my PC

if the card shows evidence of heavy physical damage, no promise it still works.