What is the strongest video card I can put in my a730n hp? The older cards ran with a128-bit and the newer models run with a higher bit rate. How much of a problem would that cause?
Bus width is irrelevant when it comes to compatibility, mainly you need to loot at your graphics slot and your power supply for immediate consideration when it comes to adding a graphics card.
You have a single PCI-E expansion slot, and a 300w PSU. Without replacing the PSU, an ATI5670 might be the best card for you if you are into gaming. If more for movies etc, than a 5450 would be right up your alley.
Your CPU (A single core P4 530 with hyper threading) would limit you from getting the use out of a videocard any stronger than a 5670, because if a CPU is too slow the videocard can't stretch its legs. Buying an overpowered card for that CPU would be a waste of money. Again, a 5670 seems like a decent choice, but if you are not running vista/7, then you might as well save a few bucks and get a 4670 for about half the price.