i have a few graphics card in mind but i dont know which ones to get please help. also if you have better ones for nearly the same price please comment
1st choice: http://www.scan.co.uk/products/2gb-gigabyte-radeon-r9-270x-wforce-oc-28nm-5600mhz-gddr5-gpu-1050mhz-boost-1100mhz-1280-streams-dpor
2nd choice: http://www.scan.co.uk/products/2gb-msi-radeon-r9-270x-gaming-28nm-5600mhz-gddr5-gpu-1030mhz-boost-1120mh-plus-bf4-game
3rd choice: http://www.amazon.co.uk/Sapphire-Toxic-1100MHz-Express-Graphics/dp/B00FOQZZ6Y/ref=sr_1_4?ie=UTF8&qid=1389449680&sr=8-4&keywords=r9+270x
4th choice: http://www.ebuyer.com/414762-evga-gtx-660-ftw-2gb-gddr5-dual-dvi-hdmi-displayport-pci-e-graphics-02g-p4-2668-kr
5th choice: http://www.ebuyer.com/489317-xfx-hd-7870-dd-edition-2gb-gddr5-dual-dvi-hdmi-dual-mini-fx-787a-cdfc
also can i run all these i have a amd a8 6600k, 8gb memory, 500 watt psu, MSI FM2-A55M-E33 uATX
1st choice: http://www.scan.co.uk/products/2gb-gigabyte-radeon-r9-270x-wforce-oc-28nm-5600mhz-gddr5-gpu-1050mhz-boost-1100mhz-1280-streams-dpor
2nd choice: http://www.scan.co.uk/products/2gb-msi-radeon-r9-270x-gaming-28nm-5600mhz-gddr5-gpu-1030mhz-boost-1120mh-plus-bf4-game
3rd choice: http://www.amazon.co.uk/Sapphire-Toxic-1100MHz-Express-Graphics/dp/B00FOQZZ6Y/ref=sr_1_4?ie=UTF8&qid=1389449680&sr=8-4&keywords=r9+270x
4th choice: http://www.ebuyer.com/414762-evga-gtx-660-ftw-2gb-gddr5-dual-dvi-hdmi-displayport-pci-e-graphics-02g-p4-2668-kr
5th choice: http://www.ebuyer.com/489317-xfx-hd-7870-dd-edition-2gb-gddr5-dual-dvi-hdmi-dual-mini-fx-787a-cdfc
also can i run all these i have a amd a8 6600k, 8gb memory, 500 watt psu, MSI FM2-A55M-E33 uATX