Is this a good PC gaming build?

[Explicid313]

I basically bought my own parts and built my own computer but I want to know if it's good or not so please give me opinions and tips on what you think and how to make it better.

I have an Intel i7 4790k, a 850 watt power supply, an AMD Radeon R9 290x, but only 8 gigs of ram. I also run windows 8.1. I also have a z97 motherboard. Any opinions?

 

[AdviserKulikov]

Plenty fine as is. You can always expand RAM later, but 8 is good enough for now.

 

[Explicid313]

I was thinking of buying 2 sticks of 8 gigs of ram. Was thinking the corsair vengeance but idk if they will work with my build or not. I think 16 gigs would make the PC perfect then.