The video driver stopped responding etc..., after changing the thermal paste, what should I do?

Question

NVIDIA

I transferred the system to another case, on the way I changed the thermal paste on the video card (nvidia geforce GTS 450). And under heavy loads (games that used to give out a few fps and a test for osst), everything crashes and the message "The video driver stopped responding and was successfully restored" pops up. At the same time, the temperature did not rise much above the norm, the radiator is hot, that is, as far as I understand, the contact is normal.
However, in other games, the increase is generally noticeable, you can turn on the maximum speed, where you previously had to run at low speeds.
Driver installed fresh.