While the integrated graphics core in the A8-3850 is more powerful than the graphic core in the A4, the A8's graphics core is still weak compared to desktop graphic cards.
The A4's graphics core is almost equal to a desktop Radeon HD 5550. The A8's graphics core is like half way between a Radeon HD 5550 and a Radeon HD 5570. Those were not even considered gaming cards when they were newly released.
I would highly avoid it and not recommend playing at that resolution. If such a cheap apu was that effective at that resolution, buying a gpu would be pointless. theres a reason why low end gpus still exist.
See following for benchmarks of the Radeon HD 5570 which is more powerful than the A8's integrated graphic core. Also, the test rig has an Intel i7 920 @ 3.8GHz. All games have been maxed to "Ultra", the highest graphic settings possible in games.
At that resolution the only thing sort of playable will be lowest presets, considering Llano is rather crude in its design and to be superseeded by a Trinity soon I would rather wait for a A10 varient if budget end gaming without a discrete card is required.