I have read many threads about computer server power supply conversions.
Some people are scared to death to do this and think it can be very dangerous.
I for one think that server PS's are the best bang for the buck you can get.
I don't know everything but I do know enough about electricity to safely convert these PS.
Some people are still confused regarding the grounding and tying 2 together in series to get 24V.
To get them to work in series (tie the + of one to the - of the other) the grounding in the supply needs to be modified.
The way they are made is the negative side of the output is internally ground to the case.
And when you connect the + from one PS to the - of the other PS you are essentially shorting the + and - together.
This is because the cases are wired together through the ground wire in the power cord.
You would never disconnect the ground coming from the cord to either PS case. You are just asking to be shocked.
If something in the PS on the high voltage side shorted out and touched the metal case you could be electrocuted.
The only way to make this conversion safe is to disconnect the DC ground in ONE of the PS. They then can be used in series to get 24V.
You can let the cases touch each other because they are internally wired together by the cords ground wire.