R9 290 Windforce (Possibly underperforming)

I'm relatively new to the pc side of things, but my graphics cards sometimes performs "Alright" (around 60fps) but then after a reboot i get around 100fps.
All my drivers are up to date, this could just be me being self conscious but i don't know. 
Any reply at all will be greatly appreciated.   
(I used BF4 for the benchmarks.) 

System specs ? Maybe it has something to do with background processes. I guess thermal throttling is not an issue.

Intel i5 4670K
Msi Gaming Mobo B85-D43

I'm so confused on what to do ahaha 

It's probably back round processes, I'm currently having the same problems although as I mainly play cs go which goes from 300fps to 250, i don't really care to mess with it. This is on a Gtx 770 4gb and Fx 8350 btw  

Does it effect other games or just BF4? It it's just Battlefield then it's probably the game, i've got a similar issue with my ASUS DCUII 290x crossfire setup, all I need to do is restart the system and it runs ok all day, other games don't cause that issue for me.