You will not be able to do a fusion of intel chipset and a Gt 620
=> For that You will have to buy a AMD A series APU and a AMD graphic card
=> AMD will be launching new generation APUs which will be the successor to the famous trinity series APUs
=> These will be capable of crossfire with HD 7*** series discrete graphic cards
=> These have an in built HD 7*** series graphic chipset
=> Incredibly powerful