First post, by HangarAte2nds!
I will be building a VLB 486 in the near future and plan to use a modern PSU. On a 500W ATX power supply, 120W are split between the 3.3V and 5V rails. Since it is VLB, the board only gets 5V and 12V. Some 3.3V may be used by drives but it would be small since that voltage is only used for signaling. The CPU itself runs on 3.3V but via a voltage regulator fed 5 volts. My gut says that 120W split between 3.3 and 5V would be sufficient for any 486 build and probably a Pentium as well. The amount of 12V power available is closer to 400W and that is definitely not a concern. Can anyone confirm the soundness of my assumption with experience? I would hate to end up chasing my tail over an electrical supply issue if there is some potential problem.
I seem to remember I had like an 80W PSU when I built my first PC back in the day, also for a 486...