I'm purchasing a new power supply for my Pentium II, Voodoo2 12MB (SLI) rig.

For the Voodoo's part, I need to know two things to help calculate my load:

1) the max wattage they can draw
2) more importantly, the max amps (A) they can draw over what rails (3.3V, 5V, and/or 12V).

Knowing the power specs of a single card and doubling that will be good enough.  Trouble is, I can't find this very important information anywhere, including in the documents listed on this site.

Thanks.

For a system like that, any decent PSU should be ok, I think that even a small format 90 W should be able to provide the power, if it's not too aged (a PSU tends to loose power in time). A 200-300 W should be more than enough, but try to stay away for generic brands. Brands like Fortron, Chieftec, Enermax, etc are always a good choice.

I don't know the exact power requirements for a Voodoo2 card, but I doubt it's more 20 W, the PCI slots can't provide too much power, and since V2 doesn't have any other way for taking power, it's limited by the PCI slot. PCI 2.1 is 3.3 V, some implementations allow 5V, but I'm 99% sure that Voodoo2 use only 3.3V line.

I'll less worried about watts and than I am about amps.  Unlike modern systems, systems of the PII Era drew most of their power from the +3.3V and +5V rails instead of the +12V.

FYI, this is not a typical system for the period.  It will have two 5400 RPM IDE HDDs in RAID, one 7200 RPM SCSI HDD, one IDE RAID controller card, one SCSI controller card, a SoundBlaster AWE64 Gold with fully expanded memory, 3 DIMMS of RAM maxing out the board, a Matrox Millenium 8MB AGP card, and two 50-pin SCSI drives.

Unless you plan to put in a very small PSU, I'm confident your Hard drives will consume more power than the SLI setup.

Back in these days, the cards didn't draw significant amounts of power (couldn't do anyway, as they were limited by the PCI bus power supply), therefor I don't see any problems with any halfway decent PSU.

PCI Bus electrical specifications :

Code:

Supply  Min. Voltage  Max. Voltage  Max. Current  Max. Power +3.3V          3.00        3.60             3A           10.8W +5V          4.75        5.25             2A           10.5W +12V         11.40       12.60             1A           12.6W

The Voodoo2 doesn't even come near using all the power as far as I know, never heard of power related problems in these days.

Good thinking.

Where did you get the spec?  Other details from the source may be helpful to me for other projects.  Are you sure it's the right PCI version (for Intel 440BX chipset)?

The Peripheral Component Interconnect Special Interest Group (PCI-SIG) is a good address :

http://www.pcisig.com/specifications/conventional/

a normal Voodoo2 card only draw less than the half
Q3D have carss with 2 Chipsets and TV-out and 2D-Module in one Slot

what exactly, idk

Just buy one good 365 or 400w powersupply, then when in future you would like to try out some other platforms, you can just use that one. Bit of future proofing never hurts.