jasonyaputra

Then you need to talk to Lenovo about that.
 
Look, we're giving you something to try. If it helps, you know what the problem is. You literally have nothing to lose by trying. You've got all the symptoms of thermal throttling.
 
It's entirely possible that a technician knocked the heapipe and cracked the thermal compound. So, if it worked before, you sent it to them, and now it isn't? Then it's probably fair to assume that whatever service they'd done on it may have resulted in this new condition.

If your seeing that, then your CPU thermal throttling, which unfortunately is quite common with Laptops. I would take the back shroud off your laptop and give it a good cleaning with canned air. 

Linus isn't going to help you.
 
The problem is that it could literally be anything.
 
You need to give us as much information as possible. Download MSI, run the OSD, and monitor EXACTLY what is going on with your clock speeds, voltage, temperature, and utilization of both CPU and GPU when this occurs.
 
It could be anything from bad drivers, to background programs, to failing harddrive, ect...
There are a lot of issues that could cause FPS to dive in a game that aren't related to the GPU itself.

Sounds like Thermal Throttling. Go download Realtemp and monitor your CPU temps. For GPU monitoring, download MSI Afterburner and you can turn on OSD to monitor temps in game for both CPU and GPU. 

cpu might be get to hot or has to much load resulting in a bottleneck to the gpu hence the performance drop

OK found something.
http://kunmii.blogspot.com/2015/09/possible-solutions-unexpectedstoreexcep.html

You bought a faulty unit. RMA it asap.
There is nothing you should nor can do to fix it, as:
a.) it would void warranty
and b.) its most likely a broken heatpipe, fan, or bad thermalpaste placement. All of which would require a total dismantle of the entire laptop.
 
Your CPU is overheating, hard.
And your GPU also seems to run around 10°C~ hotter than it should be, so both are overhating. HOWEVER the GPU "overheat" could be caused by the fact that your CPU runs 95°C hot, which puts additional heat into the system, which will speard to the GPU. So again: CPU overheating is 100% certain, GPU could be, slightly or just caused by the CPU overheat.
 
According to this video:
the CPU does not even go above 85°C in Prime95 after 15min of stresstesting.
If yours overheats after 5min of Dota, this test would most likely make your system shut itself off entirely to stop it from killing the CPU.
 
According to this review:
http://forum.notebookreview.com/threads/a-review-of-the-lenovo-y50-i7-4700hq-gtx860m-8gb-ddr3-1tb-wd-hybrid-hdd-intel-7260.755175/
The CPU stayed at around 83°C at a 64player BF4 match, which is easily 3x as taxing on the CPU than CS/DotA 2.
Also note here the guy claims his GPU never went above 66°C, while yours apperantly almost hits the 80°C mark and again, BF4 is also way more taxing on the GPU than the games you play.
 
 
and to why you dont experiance any FPS drops on unigine benchmarks -> they dont stress the CPU only the GPU.
Your CPU usage while running any of them will probaly be around 10%~.