Hellish day. 5 computers in my network started getting random bsod and random time, sometimes 1 or more hours apart, sometimes few minutes. After middle of the day only 2 computers of the 5 keeps getting bsod. Is this somekind of virus, I ran few scanners didn't found anything. And why this is happening only today and only these computers. Wtf

Start debugging, replace parts if you have spares, check logs! they are useful!, what software are they using? OS? updates? what are the differences and similarities between them?

@Gregozor2121 OS: Windows 7, Windows XP, Windows 2012 r2, Windows server 2003. On consumer os running scada, on server old server just files, on 2012 some billing and other programs. It could be virus. But why it stopped on other computers. No blown capacitors, no dust.

@nonsleep1 Which OS'es were affected?

@Gregozor2121 That's a strange thing. We have 6 computers in the network running win 7, only 1 computer was affected. We have 2 computers running win xp, both of them was affected first half of the day, later on only one kept crashing(one computer with win xp stopped crashing at same time as computer with win 7). It looks like an attack, but only 1 computer of win 7 group started crashing. All updates and av are the same on all computers with win 7.

Have you checked the logs?

@Gregozor2121 yes, found nothing interesting.

@Gregozor2121 One more strange thing. I tried to change wifi password for our main router. And it just went nuts, dhcp stoped working, wifi stoped working. Router is pretty old, maybe he can somehow fuck up some computers in the network?