I have a server power supply model HSTNS-PA01. I will be using it to power hard drives for a NAS. The problem is, this PSU outputs 12.8V with and without load, which is out of the 5% tolerance allowed for computer components. I want to lower the voltage to a safe 12.5 (or even lower). After doing some research, it looks like people have been using this PSU for RC chargers and alike by raising the voltage to 13.7 and such. My only hope now is that by using the voltage sense function I could make it realise it's out of spec for a 12V PSU. My question is, will I hurt anything if I connect the +12V RS+ directly to the 12V+ output, and the +12V RS- directly to the GND and powering on the PSU without any load attached? If it would, what should I try to lower the voltage by using the logic level pins?
It will not hurt anything to connect the +RS to the +12V and the -RS to GND. In fact, as shown below, there is probably already an high resistance internal connection so that the supply will be able to regulate without external sense connections. Connecting the sense externally with wires overrides the internal sense resistors.
Assuming that the supply is not defective, since the supply is putting out +12.8V both unloaded and loaded, the output voltage may actually be set to +12.8V. This page about Hacking HP Common Slot Power supplies - 12V@100A may be helpful in working with the DL580. Unfortunately, I could not find any specific information about setting the output voltage.