The user "xandrios" on RCgroups.com has composed this briliant how-to on getting a server-psu to be used outside the datacenter ;-)
5vsb - The sb stands for standby. It means that the 5v will be available in
all modes of operation. Powered up, powered down(standby) and during a
fault condition.
Bringing that up, this is the method I used to find the correct pins
to power up this supply. It also works for a majority of PS units out
there.
With power off and testing each pin to ground.
1. Exclude any pins that are common to each other(including ground
pins). Usually these are the 3v and 5v rail pins. They also show the
same resistance.
2. Exclude any open pins(pins with no resistance that don't connect to anything).
3. Exclude any pins with a value below 1k ohms and above 10k ohms. From
my experience, I've found that the pson and pskill resistance usually
falls between a 1k and 10k range.
With power on.
4. Exclude any pins that show no voltage.(pson and pskill are held
partially TTL high or just not grounded. So they show some voltage on
them).
This will usually leave between 4-6 pins.
Use a .5k ohm resistor on each of the individual remaining pins and
connect each to ground. The power supply will usually power up at this
point.
Disconnect one resistor at a time from ground.
If the PS remains on after a you disconnect a resistor from ground, then
the remaining pins contain the pson and pskill. So keep it disconnected
from ground.
If the power supply turns off, then the disconnected pin is either the pson or pskill. So reconnect it to ground.
Repeat this process until you find the pson and pskill pins.
In some cases the PS will turn on with a fault.
If this happens then disconnect one resistor(pin) at a time from ground
to find the one that is causing the fault. Then continue with the
process above to find the pskill and pson pins.
All above is from:
RCgroups.com