Thermal throttling was my issue, check with afterburner to see if its yours, and see where to go from there. The Hyper 212 EVO, though I installed it, is too big for the case, btw.
This isn't a question, but a short summary of what I did to eliminate frame dips. Nvidia control panel: First of all, if Nvidia, go to Nvidia control panel and change a couple of things, like set adjust image settings to "performance". Then (or before), go to manage 3D settings; global properties and set power management mode to "Prefer maximum performance", and change texture filtering qualities to "High performance". You could also turn vsync off if you prefer. If AMD, do the equivalent.  Windows: Type into search bar "edit power plan" and press enter. Click on "Change advanced power settings" and select on the top bar "High performance" You could also set a power plan to your liking by typing "choose a power plan" and selecting "create a power plan" on the left side. Summary of free "improvements": The settings above seem to help in less demanding games, but the Inspiron can be very finicky and games that should be able to run fine stutter severely. So, the mileage may vary.   Internal (PAID): There are a couple of problems with this specific computer, them being the ram(8gb), cpu cooler, and power supply(460w). I'll list them in order of miniscule to big problems. (PSU) This is for the 460w. This isn't necessarily a problem with the frame dips in games, but if you put a card in that drains more power than the OEM 1080 they listed was compatible with the computer, it could cause a variety of problems from frame dips all the way up to your computer not starting or frying components. I upgraded from the 1060 3gb to the 1660 super and it works fine, but I wouldn't go farther than a 1070, and even that is pushing it. (RAM) 8gb isn't really enough for higher end games nowadays. Get a second Samsung stick or replace with something new (and supported) and run in dual channel. (CPU Cooler) This is what fixed my massive stuttering. Using MSI afterburner, I saw that my CPU was getting into the high 80's and up to the mid 90's, and was thermal throttling in every semi intensive game. The stock cooler they use isn't good for gaming. The problem is installing a new cooler can be a , because you won't know if the board will accept it and you can't get into the bios to change fan speeds or anything. After installing a new cooler, my cpu stays at the high 60's and low 70's even in games like metro exodus. So, use at own risk, but this helped me.    TLDR: A couple of fixes for the 5680 that could be as small as changing power settings or installing a better CPU cooler. Installed a new CPU cooler, and my stutter/frame dips are gone. CPU overheating was my issue.   PS: Don't get the CM hyper 212 evo unless (Like me) you are alright with cutting the side panel out. Its to big for this case.  
Dell Inspiron 5680 severe fps drops fix.