I recently bought a new evga gtx 550ti gpu for gaming. It works great so i decided to buy another 1 to run it in sli. My motherboard is asus m4n75td. After buying the new 1 i installed it alone in the pc and ran video memmory test to ensure that the card was good. It passed without any errors. So i finally decided to place them in sli since they both passed the tests. After placing them into sli and installing the latest drivers 285.62 i noticed that everytime i shut down my pc windows shuts down but the pc doesn't power down (all the fans and lights remain on). I thought it was the drivers so i tried the older ones with the same problem. I finally decided to put the computer to sleep and all the fans powered down when it entered sleep! So i searched online and tried allowing the computer to power down the IEEE 1394 bus controller which didn't work. I reformatted my system with the same windows 7 x64 which was an epic fail cuz the problem remained. If i remove the drivers for the cards the computer powers down with no problem. If i use 1 card with the drivers the computer powers down as normal. The problem only arises when the cards are in sli and the drivers are installed. Thanks for your help in advance guys!