And while the video can be on board it's also a common thing to plug in a card and use that.
Just check your Dell Docs to see if there is a slot in the machine. The 5450 is selected not so much for gaming but that it won't have you replacing the power supply.
Bob
I want to upgrade my Dell Dimension graphic card.
Will the SAPPHIRE HD 5450 512MB DDR2 PCIE HDMI
http://www.sapphiretech.com/presentation/product/?leg=&psn=000101&pid=313
will it fit in?
I am not a technical expert and I can read that the graphic card in the Dimension 2440 motherboard is "on board" - will it work?

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