Question What's wrong?

Mar 31, 2020
Hello, I bought a PC from my friend, it's 1 year old, it has GTX 960 4gb, I5-6400, 8gb ram, i watched some videos on youtube, the pc was good it ran gta v on ultra 70fps, but now, when i have it, it runs gta v very poorly, on low it runs on 40-50fps, does someone know where could be the problem? I tried reinstalling windows multiple times, but it didn't work.
that is a rather low quality setup. you are getting around the FPS i would expect.

but, there are many factors that can effect gameplay besides actual hardware.
what resolution are you running the game?
are your Windows Power Options configured correctly?
are all updates installed correctly; BIOS, motherboard/chipset, GPU, Windows, hardware, etc?
is Nvidia Control Panel configured correctly?
is your GPU manufacturer's control software configured correctly?
do you have unnecessary processes running?
are all BIOS options configured correctly / thoroughly maximized?
what type of disk is the game installed on?

are you saying that your friend made a video of themselves playing with this same system or that you have found video of a similar system playing?