who is the lowest graphic card

[Turtle The Cat]

that the i5 3570k can use without any bottlenecks
http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.html
that is the link to the graphic card heirarchy tomshardware provides for us

 

[jay_nar2012]

Well just be aware that a CPU can be bottlenecked by a GPU.

I would say this point is at (based on the HD4000's equivalent), the 'lowest' GPU it could probably work with without bottlenecks is around Intel HD2000 - HD3000's equivalent range, i could be wrong so don't quote me on it as im not an GPU expert but older GPUs will be more prone to bottlenecking the CPU.

If you meant in terms of the CPU bottlenecking the GPU then i would say no GPU is really bottlenecked by this CPU as it is still considered a powerful CPU, even the GTX780ti shouldn't be bottlenecked by it.