24V to a case fan?

[Nebuchadnazzar]

Which line (colour?) is the -12 line. Cause i have a similar problem, but i don't want to open my psu to trace the lines.
lol mines 48v though
http://www.comairrotron.com/dcfans/MuffinXLDC.htm

 

[adrian nelson]

thats a nice fan
as for the -12v wire blue, purple, white
have a look in your mobo manual for a pic of an atx conector, and find it that way,
or if its a AT psu the 2 center lines on the p8 conector are +12v (yellow) and -12v
and dosent "Caveat emptor" meen buyer beware?

 

[Koooler King]

Because they share a common ground, the +12V and +5V lines cannot be connected in series to produce 17V. Draw a schematic where the +12V and +5V share the same ground, and try to put them in series without shorting one. You'll see what I mean.

Actually, depending on the design of the power supply, they don't always share the same ground ... that was my caveat. Most typical power supplies today do seem share a common ground, and actually the 5V line is typically regulated based on having a small current load, then the 12V piggy backs off of it ... e.g. if you measure the 12V line with no load on either line, it can float between 10 & 14V! Add a few miliamps of load to the 5V so it can regulate (e.g. plug in a dummy hard drive, etc), then the 12V line immediately snaps to right on 12.0V (+/- .1V or so).

It really depends on the power supply design ... maybe it is not so possible today, but I do know of modders in the past successfully putting the two lines in series to achieve 17V. It was just an idea, including odd mixes where I even heard of people using them in a differential way to get to 7V. Go figure? Caveat emptor. Good luck!

KK

 

[four4875]

you CAN use the 5 and 12V lines to get 7V. use the 12 as + and 5 as -. and to get the 24V for that fan use the -12V and +12, giving a total difference of 24V. the PSU should be able to handle the current. right now im runnin a 12V papst fan off of 24V and its doin fine (the PSU)