All those parts are compatible with each other. But any graphics card that requires an external PCIe power cable (HD 6770, GTS 460) will require you to upgrade your PSU. 300W is border-line weak. Use this PSU calc to find the size you need.http://www.thermaltake.outervision.com/
The board amuffin suggested for you would be better IF your case can accept a full size ATX board. You mention your case as being a mini ATX.