Well, I've solved the issue.
I cleaned some dust out of the fan blowing air into my CPU and unplugged and removed 2 colourful fans from the back of my computer. That did the trick, I'm not sure if it will stay that way but so far so good. The core temp and the 'Temp1' are high still when I play games but the lag's gone for now.
I guess I need a 800 PSU.
Thanks for the help anyway guys. :)
