new gpu but no display????

[manoob]

bought a hd 6450 gpu today. but after placing the new gpu in pci express motherboard I don't get any thing on display. the old card works fine.
I have a ga-p43-es3g gigabyte motherboard. I updated the bios using @-bios update. to f14 or 15. still didn't work. the new gpu works fined in the shop.
I have a intel core2 duo and 4 gb ram,
why isn't this mother board working with new gpu??? the psu is 500 w and the gpu shouldn't have a problem with it.
the machine starts and there are no bleep sounds. just no display.
is it because of motherboard is old and wont work with new gpu`s?
are there some updates I have missed???
please help
thanks

[TFisher]

Have you connected the monitor cable? Sometimes one forgets.

 Were you using the onboard graphics before the new card?

if so,you might have to disable onboard graphics in bios.

[manoob]

hi thanks for reply. managed to fix it somehow. I tried a different hdmi cable. and it worked. which is weird, the other hdmi cable works fine too with everything else except the 6450 gpu!!! it works with older gpu and my tv .
now a new problem has showen up as the gpu has onboard 7.1 soundcard. the sound the comes out goes to different speakers than it should. like  front and back speakers sound the same!!  I reckon its something to do with windows drivers or codecs settings. so its still more trials till it works

[welshgrad]

go to amd site and find the amd driver sweeper. it will wipe all the amd stuff off ur comp. start fresh there. fixed my hdmi sound issue