which one is best?
i am plannig to buy new pc with i5 processor...
is hd5570 enough for playing new games??
and also hd5570 comes with 2gb and supports directx11
or else suggest any best card..
The HD 5570 is a little slow for serious gaming, you should try for a faster card.
A good place to start a search for good cards is the THG article on the best video cards for the money, updated monthly to reflect new prices and new cards. Note that it includes links a very brief description of the performance level of the card plus links to reviews with detailed performance benchmarks, most often with comparisons to other cards:
Also note that on the first page of that web site is a promotional code to get $10 off your first purchase of $50 or more at newegg - should help reduce the cost of a new graphics card. Note that it expires 8/31.
Also, if you are buying a new PC with plans to upgrade the video card, pay careful attention to the size of the PSU as most systems come with a PSU that is only a little larger than what is required for the existing system and, even when the total power is adequate, often don't provide enough power to the 12v leg. Additionally there is a wide range in quality between manufacturers.
Additionally when you think you have identified the system you want, post the information - name of system, PSU wattage, and video card make and model - to this forum and people can help you review it, although it will be difficult to give a definitive response without knowing the model of the power supply which you will likely not be able to get until you buy the system and look inside.