Everytime after I turn SLI mode on for my pc it switchs over fine and then when I start up my game world of warcraft my pc freezes up after 10 mins or so. I get forced to do a hard reboot. I have windows vista 64-bit check my profile for my hardware specs. I updated to the latest nvidia graphics drivers but it didn't help. My motherboard has the vista nforce driver version 15.17 . I have a 600 watt power supply and my ram is only 5 months old. I don't think any of my hardware was factory overclocked. After I rebooted the first time I tried my game again and I still crashed had to hard rebot again. I came back on went to internet explorer and my mouse started lagging around on the screen and then my pc froze again. I eventually had to switch sli mode back off and now my pc works fine.