hi is a single 240 mm radiator loop enougth to run a phenom 2 965 and a hd6950 both oveclocked or do i need to run the gpu on its own loop
Short answer no,
long answer, check out the W/c sticky to determine your Tdp,
its possible to run a Cpu/Gpu loop on a 240, but it would need to be a very good rad in pushpull with louder fans and no overclocking
minimum I recommend for Chip and gfx is a 360, if overclocking then 360+240 min.
but by determining your Tdp you will know how much rad you NEED, and if you want a quieter system, more rads allow more and slower/quieter fans so you can work out what radspace you WANT
you can run both on the same loop btw, theres no need to add the expense of a second pump/res to the list, and one large loop will perform better than two smaller ones, set up correctly of course