Taco, that is going to be pretty tough with only a 160w power supply. Your CPU alone is going to be taking up 45w at normal operation. It will require a larger power draw as you are gaming. That doesn’t leave a lot left over. The graphics card you are looking at is requiring a 400w Power supply with a 450w recommended power supply. I have a feeling if you try this, you will cause issues with your CPU. In fact, your board may not even power up when you try installing the new card without a larger power supply. Also, the power supply that is included with your current PC most likely doesnt have the video card 5v power adapters you are going to need.
The HP motherboard that is in this mini PC can handle the Graphics Card, however that is if you are using a much larger power supply. The design of this mini-pc is for space constraints and unfortunately not power (such as gaming). My recommendation if you really want to do something is to pull everything out of that case, add a new power supply (700w) and then purchase a 6x5x (or higher) series or 7x5x (or higher) series ATI video card. Then get yourself a cheap (but nice) ATX case and add everything back into it.