You could increase to a 1000Gig's if they made one.
A graphics card has it's own graphics processor, and graphics ram memory. It runs independent of the System Resources.
The Processor and Ram Memory.
Chip and Chipset are slang terms for I.C.
The graphics I.C., or graphics chipset, is a GPU,http://en.wikipedia.org/wiki/GPU
A GPU can be mounted directly to the motherboard, and use some of the system resources. Integrated graphics.
Or it can be mounted to a removable graphics adapter card.
IF there IS a 'bottleneck', it will be your Processor, and amount of Ram Memory.
Should have at least 2GB of ram memory
It will take up to 4GB. can also support DDR2 Sdram at 667MegaHertz. (PC2-5300)
Intel 945G motherboard chipset.
Intel 82945G Northbridge chip,
Intel 82801GR Southbridge chip. (ICH7R)
Supports Intel Core2 Duo processors, with a Front Side Bus of
UP TO 1066MegaHertz. (FSB up to 1066MHz)
Intel 945G chipset was brought out in 2005. This means to me, the PCI Express technology used on your motherboard, is
PCI Express 1.1
I would stick with the graphics cards using PCI Express 2.0 technology.
I've read reports where the PCI Express 2.1 cards, weren't 'playing nice' with motherboards using the PCI Express 1.1 technology.
Unless you just wanta' experiment? Who knows?
How many maximum Watts is the Power Supply, capable of delivering at 80 percent, and how many Amp's does the 12 Volt power rail have?
(If there is more than one 12 Volt power rail, you can add together for the total 12 volt Amp's )
See what the minimum requirement is for the Power Supply. make sure you have MORE than enough.
Also if the graphics card requires an additional power cable; make sure your Power Supply has it.http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=555358&CatId=3669
But the minimum wattage for the Power Supply is 450 watt.http://www.newegg.com/Product/Product.aspx?Item=N82E16814129203
Power Supply? 500 Watt.