Random FPS drops in teamfights.

Hello, I have recently purchased a powerful new laptop (Asus Rog g751) with a 4th Gen Intel® Core™ i7-4710HQ processor and a Nvidia Geforce GTX 860m graphics card but for some annoying reason I am getting random FPS drops from a high 200+ FPS (without vertical sync but highest settings) to a low 20 FPS drop during periods of high performance such as team-fights lasting ~1-2 seconds. I have tried many things to fix this issue including messing with all settings I could get my hands on including the LoL settings which despite lowering the graphics it still has this drop issue. I have tried messing with the Nvidia 3D settings which provided seemingly temporary relief but the issue eventually came back. And I also tried a complete factory reset multiple times which surprisingly fixed the problem for a short while (~1 day) then the issue randomly came back again without making any setting changes. -I have updated drivers and reinstalled drivers as well as tried older versions of drivers. -I Have re -downloaded the LoL files. -I have made all the changes suggesting in the FPS troubleshooting LoL guide -Temperature is fine given it's a brand new PC -I have ran a few virus scans but the probability it's a virus is very low given it's a new PC. I've noticed that changes such as vsync off and some lower Nvidia 3D settings make the problem seemingly less frequent but it still occurs. I would greatly appreciate any advice as to what I can try to fix this problem. I would like to think that my PC should be able to run LoL with ease even on the highest settings which it does apart from these FPS drops. Thanks very much in advance! :) -Conrad P.S I have already submitted a ticket to the LoL support website and they give me a generic copy and paste answer telling me to try everything I already have tried.
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