gtx 960m performance issues (underperforming in every application)

first off some info: my system is as follows: i7 5700HQ cpu@2.7ghz, on board gpu: intel HD graphics 5600, Nvidia gpu: geforce gtx 960m, 8gb ram @2133mhz, running on win8. The thing is, I usually have less than average performance in almost any game. And i cant tell what is the problem. I have just recently updated my drivers, and well, sometimes thats a problem as well for i always get the "cannot find compatible hardware" bullshit when i use nvidia installer, so i have to somehow manually install the drivers. Anyway, my brother has the exact same laptop, and he is able to run games faster with outdated drivers. I always use my laptop plugged into power, I have selected the proper power plans for max performance etc. How can I begin to diagnose what is wrong? edit: yeah, I should probably mention those, I have uninstalled with DDU, reinstalled, my gpu temp is usually around 70 degrees c when its under load, and i have that little indicator thing at the system tray to check if the program i am using is actually using the nvidia gpu instead of the onboard one. At this point i am really confused and dont know what to do. I have the exact same settings in nvidia control panel as my brother's laptop, and my screen was broken a few months ago, so when I had it replaced, the tech service also cleaned the insides plus applied some paste I believe. So maintenance wise, it should be as good as it gets. The problem is: the other laptop can run a game at 30 fps or So, whereas I get about 15. Really frustrating. Another edit: i have submitted this a few days ago in another thread, I may have made some progress. In the past week i have tried numerous stuff, had no effect whatsoever, however a couple of times, after restarting the laptop, the GPU DID work properly, and i had the same performance as my bro did. And after i restarted the laptop once more, it reverted back to the low performance. I didnt change any setting, and whether it works with low perf. or high perf. i can see in the sys tray icon that the games i play are using the nvidia card and not the onboard one. One other thing i have checked, is that my gpu is utilized 100% (according to my research this is normal, with about 70 degrees temp.) and my CPU usage is rather low (with a max of 51%, and average of 20% throughout the testing of the game i.e. : opening the game, shooting stuff, making sure i have low fps, then quitting the game) My gpu temp is also around 70-75 degrees C, so i dont think this is a hardware issue. I think ill try a different windows, for right now i am using a pirated copy of win8. ANY help would be greatly appreciated. And yet another edit: I am getting 14-15fps in Heaven Benchmark 4.0 on high settings (not ultra), no tesellation, no anti aliasing, 1920x1080 resolution. There is clearly something wrong.