The video card was bought few months ago, so it's technically impossible that it's dying. Plus, I have only the issue with a Second Life.
Any my mistake, I forgot about "HD" in the card name. It's HD 7790, so it's a quite powerful card. My power supply is Chieftec 700w, so it's not a no-name.
I can play on this card any game and absolutely nothing happens. It runs BF4 on high details with stable 30fps. Even, when I play SL, it's fine. Everything is smooth, FPS is stable.
It happens ONLY, when I log off from SL.
I have f.lux installed, but I don't use this so often. It's disabled, when I play SL.