Pretty sure there is no A3 3400, so I'll assume you're talking about the A4-3400.
First of all, this is a dual-core with no hyperthreading, and it is one of the first-generation APUs from 2011. It is also the bottom-line APU, meaning it is exceedingly weak. If you seek to game on it you will not be able to run anything that is more hardware taxing than Minecraft. I would not recommend you buy this.