You only need to know a thing: more RAM will help you more with bigger programs and with video games. Currently, if you have 4GB of DDR3 RAM, then you’re fine, but DDR4, with clocks that go up to 3200MHz and capacity up to 512GB for a single piece, will greatly increase the karma of your gaming computer. DDR4 is not backwards compatible and works best with the Intel i7 series and the FX series processors from AMD.
Soon I’ll build me a new gaming PC, albeit a modest one, but that will use a AMD FX processor, an ATI RX9 video card and DDR4, of course.
Now, in regards to monitors, try to locate one that offers at least HDMI or even DisplayPort. Linus from TechQuickie explains why: