ive got a acer f690gvm motherboard with a built in ati rad x1250 built in and a nvidia geforce 8400gs card. what i wondering is can i upgrade my nvidia for a ati rad hd 4350? would my motherboard support the new card?
As long as you get a card that fits in the same slot, and the power supply can handle it, then yes. The board likely supports the PCI-E interface. Check the power supply to make sure it has enough wattage and amperage. Whatever video card you are looking at should have a minimum power requirement posted somewhere.
As far as I can tell, your motherboard does have a PCIe slot and can support any current GPU.
A 4350 will work just fine but I would recommend against this upgrade.
The only reason for such an upgrade I can think of is to get better gaming performance.
Neither of those GPUs are any good at gaming.
The MINIMUM upgrade I would recommend would be to a 4650/4670.
Both are massive upgrades from what you are considering and are designed to be extremely low power.
If you decide to look into any faster cards, you will need to post specs on, and probably upgrade, your PSU.