Dell latitude E6430 - Works below the base frequency of the processor, lags

Hello, my Dell Latitude E6430 began to slow down sharply, I come home from school and I see my brother playing Minecraft, I see and it lags wildly, I asked him to go to gta 5 and there too lagged, although my laptop with this coped and play was pleasant, eventually when I sat down and began to do diagnostics, then in the entrance of it I realized that my processor is looping exactly at 2. 5 GHz (Intel core i7-3520m 2.9 GHz, from turbo-boost max 3.6 GHz), although there was no such thing, I also saw that it does not work at 100% but at 86 and for this it was immediately clear why the games lag, BUT, even many reinstallations of Windows, sometimes the processor began to work as it worked, but after half an hour it was rebuilt as it was up to 2.5 no more. Then I read a bunch of articles and because of what can be, eventually on the forum 4PDA people said that you need to check the power supply of the laptop for defects, in the end I noticed a funny picture, the block that “modernized” in the service, that is, removed from it the film that held the case, and all glued with glue, then examining it I saw that the central pin barely as a hold, and the glue that held it - melted:)

In the end I took the laptop to the service, there soldered the pin and fixed my power supply, but the result did not give, it worked as it worked, in the end I ordered a new one, but even with it the laptop did not start working on the base frequency, in the end without paying anything I took the laptop, now I reinstalled on it 11 Windows LTSC, and began to experiment with it, and today I made it work 3 times at 3. 4 ghz and at 100%, but this is a false value as in games it still holds a maximum of 20 fps, dug all the internet, absolutely all, but nothing even in the guides I could not make it work as before, by the way the processor trotling no as the temperature is kept at 50-75 yes and in the winter was on cleaning and replacement of thermal paste, help me please

https://youtube.com/shorts/cC5k2MwuD0w