You are encountering thermal throttling.  Basically, the CPU and/or GPU temperatures are rising to a point that the system considers dangerous, so it significantly cuts back their clock speeds (which kills your frame rate) until things cool back down.  Then it allows them to run at full speed again, until the temperature gets too high, etc etc.  If you haven't already, make sure the vents are and heat sinks are free of any dust that might obstruct airflow.  There are also some systems where this is simply a byproduct of their design.  My XPS 15 does this when the CPU and GPU are under heavy load simultaneously, such as when gaming, and Dell's position was basically that it's not a gaming laptop.  However, that shoudn't be happening on the Inspiron 7577 since that system IS marketed as a gaming laptop.

Can you help me with any software that can do that? It will be very helpful.

I'm not sure what you're looking at to conclude that GPU temps are fine, but when I encountered this issue on my XPS 15, I found an application that checked the speed and temperature of my CPU and GPU every 30 seconds and logged the output to a text or CSV file.  I started that application and then played a game for a while, watching my FPS drop and then recover, then drop again.  After about an hour, I stopped the game and looked at the results.  It clearly showed that when the CPU and GPU reached a specific temperature, the clock speed on both was cut back significantly and held at that lower speed until the temperature dropped to another specific level.  Of course Dell still gave me the "The system is working as designed" answer, even though they significantly improved the cooling on the next generation model....

But based on the behavior you're describing, I really don't think this is a BIOS or driver issue.

Thanks for the post. 

But my GPU temp are very normal and this happens right from the first game.

Also dust accumulation to a 1 month well protected laptop is alarming.

I really hope this is not the issue. I recently updated my BIOS to 1.3.2 which is now not even there is the DELL Driver list.

I really wish this can be solved. The service center guys have already let me down, saying its working fine.

Hello Again,

Monitored my GPU temperature using Hardware Monitor and the temperature was static in 84deg c.

And I kept getting stutters. 

Any idea?

Hmm, ok.  I definitely wasn't expecting that result.  In that case I would probably perform an OS reinstallation.  It sounds like that service center recommended that, but it's not clear whether you actually did that.  If you didn't, fyi you can always capture an image backup of your current setup using an application like Macrium Reflect Free so that if the clean install doesn't fix anything, you can always quickly restore back to what you have now rather than having to do the whole clean install routine for nothing.

Hello Again,

Been trying to find a solution but being helpless at the moment.

Have been calling the Tech support team and things are done over and over again, with no progress. This is a 1 month old laptop and I have been facing these stutters for the last 10 days.

The Authorised service center has no clue whatsoever and did a complete flash and reinstalled all the drivers.

Request someone from Dell to see this issue. Cannot keep struggling forever with a faulty laptop with absolutely no support. Spent some hard earned money into this.

Request a solution.

I am have the EXACT same issue with my dell 7577.

New computer, worked great for a month or so, then  I see these FPS drops and stutters every minute or two minutes across all games that i play.

I have tried all the fixes too:

rolled back drivers

rolled back fall creaters update

reformatted hard drive

reinstalled windows

updated drivers

updated software

This certainly appears to be a hardware issue.  Dell hasnt been able to fix it with their premium support too.

Same problem here, i dont know why the problem comes up after some time using ghe machine but i found out throtteling occures when the cpu reaches 100 degree celcius. I just undervolted my cpu by -100mV via Intel`s Extreme Tuning Utility and this seems to work well for me, bringing the temeratures down by more than 10 degree and preventing it from throtteling. How ever, this should not happen at a dell gaming notebook imho. 

This should work for you, too. A few guys on youtube also switched their thermal paste, but thats a risk i won`t take.