Fans at 7v on AT psu

[jenko]

Just fitted a second AT psu for my fans i have modded it as in the how to post so the ground is no longer down to the case earth.
It works fine with fans connected at 12volts but if a i mod the molex for the fan to run at 7volt the psu buzzs and the fan stops.
The same fan and molex run fine on my old ATX psu at 7volt?

[jenko]

Bump is it ok to run case fans at 7volt? positive of fan on on the 12v rail and the negative on the 5v rail?

Works ok on my ATX psu.

[zip22]

hmm id make sure you're doing the 7 volt mod correctly, and if you are then id say the AT psu must not be able to handle it and i would instead find a different way to run them at 7 volts

[larrymoencurly]

Do you have a load between +5V and ground? Most AT PSUs need a minimum load like this of an amp or two this just to run properly. BTW if you apply this load with a 5 ohm resistor, be sure that it's rated for at least 10-20 watts or it will get hot enough to burn or melt stuff.

[jenko]

Thanks will try putting a load resistor across the 5v+ and ground when i get the chance.