I have a five year old Dell XPS 730 with two GeForce 9800 GX2 cards, and I was thinking about buying a single GeForce GTX 770 to replace them. What do I need to look out for? The clock speeds differ, as do the memory clock speeds, and memory bus size, etc. Are there any differences between the two cards that would prevent this upgrade, or is this really a no-brainer and I should just order that GTX 770 already?