I've attached ps -axww log.
I'm not sure why firstly attached logs (in "kernel configuration, dmesg, xf86config, xf86log and scanpci -vv are attached." message) are not enough. And also there is no problem with stability. Simply when I use nvidia-driver AND run X with it's selected AND I'm in X's terminal I have this interrupt cpu usage. When anything in the specified condition is changed (for example, when I run X with nvidia driver I switch to usual text tty via Ctrl-Alt-F2 and run top there) I see interrupts take 0 per cent of CPU.
I've written a letter to nvidia some hours ago and wait now for the answer. But I have something to lose: my hope that this damn computer would work
At least I thank you for your attention to my problem.