the evga cards should fit, you also make sure your case is big enough the 9800GT is about 9.5 inches long. and the dual slot cooler pushes air out of the case so the card itself and the other pc components will be cooler.
Both cards are the same length and the XFX 680i LT easily fits dual cooler solutions. I have one, just be sure to update bios and drivers ASAP when you get it or it will be an unstable mess. Also remember that board is a OEM board and will NOT come with connectors or SLI bridge or any other accessories. I would recommend this board: