you need to find the make (manufacturer) and model (model number) of the motherboard you are using in order to answer your own question. The number '82945G' that you posted is an Intel chipset number, not a motherboard model number. Chipsets make up only a small part of the components that form a motherboard, so identifying the chipset does not by itself identify the make and/or model of the motherboard. Many different motherboards from many different companies making motherboards (Intel, Gigabyte, Asus, MSI, etc.) can use the same intel chipsets (or nvidia chipsets or via chipsets etc.). For example, both Asus and Intel use the Intel Q45 chipset for their north bridge.
Once you identify the motherboard, you can go to the manufacturer's support web page and look it up. The pages there should normally tell you what the specifications of the board are including what type of graphics card you need. Alternatively to the manufacturer's web page, I sometimes go to a reputable online computer parts vendor like 'newegg.com' or 'newegg.ca'. Sometimes you can find what you are looking for more quickly there. Just do a search for the motherboard make and model and click on the 'specfications' tab when you get to the product details page. Whichever place you decide to look, make sure you enter the model number correctly. Even slight differences in the model number can make a big difference in telling us what parts go into the motherboard. In any case, the motherboard model number will lead you to what you want to know.
For example, look just below the copper coloured heat sink in the middle of this motheboard. Printed in white directly on the motherboard is the name of the manufacturer (Gigabyte) and the model number (it starts with a GA, but unfortunately the resolution is not good enough to see it all... but you won't have that problem since you have your own motherboard right in front of you).
Or here is an example with an Intel board. Look directly to the right of the CPU socket... there are stickers that should have the model number on it right next to the Intel logo stamped directly onto the board:
Or an MSI board where the model number is not in the same place as the manufacturer's name. It is between the first and second card slot on the left side of the board.