Awhile ago, I was running an 8800GT, then for some reason or another, the card went out. So I grabbed my old, crappy, artifacting x1950, and started using it for a bit. During gameplay, my PC would run smoothly for about 10 seconds, then get all choppy. if I went into a menu ingame, the smoothness would return, but for only 10 seconds. After getting tired of all that, I went and had my buddy lend me a 9500GT till I had the money to buy a new card. But for some reason, the same problem is occuring. As you can see in my SIG, I have all the required stuff to play left 4 dead smoothly, yet it is constantly lagging out after 10 seconds. Does anyone have any idea what the cause could be?