If you can find a R9 nano in your budget,it is the best case scenario. After there is a variety of SFF gtx 970. I don't think you can go smaller than that.
If you can find a R9 nano in your budget,it is the best case scenario. After there is a variety of SFF gtx 970. I don't think you can go smaller than that.
Maximum dimension of graphics card: 310x145x47mm (LxHxD)
Your problem will be how much power your graphics card will use.
You have 450w to work with.
A GTX960 would be a typical card.