New cpu, mobo and ram

[Swanwik]

So I just upgraded my motherboard, RAM and CPU. I already had an GTX 1070 and a 700W PSU. So I put it all together and the PC works, but it's not preforming how it should, I have high FPS in games, but as soon as some "action" happens my FPS drops below 80 maybe even lower. Let's say I play fortnite. I have 250-300 FPS, as soon as I fight someone or alot of building happens, my FPS goes bleow 80 FPS. 

 

And I am pretty sure I have download all the new drivers and softwares for the new parts.

 

MOBO: ASUS ROG STRIX b350-F Gaming AM4
CPU: AMD Ryzen 1700
GPU: NVIDIA GeForce GTX  1070 OC
RAM: 16.0 GB Dual-Channel Corsair Vengence 3000MHz DDR4
 

 

And what I find strange is that speccy is telling me that i have 4095MB and not 8000MB on my GPU, and that my RAM is unknown.

 

If there is something else you need to know tell me in the comments.