Hi Alex, I've read on the forums that 80% of CTD and lag spikes are caused by overheating video cards so remove the sides of your box and blast some dust-off(canned air) to clean the top of your video card.Play the game with the sides off. If you see some improvement, or a large dust cloud came off the top of your card, take your box outside and clean the inside completely. Don't forget to clean all fans and the power supply as well.Check that all your fans are working when you hook everything backup. It is easy to drill a new hole for a extra fan or two through the side panels across from the video card. Worked wonders for me. Hope it helps