@Karlos @Tafka @Mendark:
Hundreds of thanks for help.

@Tafka @Mendark:
Standing alone, no network, no Samba.
@Tafka:
How can I swap to Picasso96? I thought that Picasso96 was just for different cards. Does it have driver for BVision?
@Karlos:
AFAIK starting from 4.0 CGX became different product, so I just have to buy a new one from vgr.com? But what makes me 'Merely Curious' is that if it's a BUG why didn't I get a single GURU?
I think that power consumption lowers when chips get warmer. The other clue is how the processor (either 68K or PPC) behaves after detecting that it's voltage is too low. What would you do?

The answer is - it stops, being affraid to do anything. The only thing you can do to make him forget about this horror is reset.
However I can be very wrong, and cannot say that old CGX is bugfree.

Regarding tests - My Machine is at home, and I have no discs with me today, so do not expect anything from me before Wednesday... Practically even later.
Good luck and thanks