StarTech ATXPOW350DF question

[sailors24018]

I replaced a failed power supply with a StarTech ATXPOW350DF yesterday. Functions fine, but I have a question: this new PSU has a 2-wire cable (black & white) that the instruction guide does not describe. The wires are thinner than those in the molex and main power cables, and the 2 wires terminate with a 3-conductor plug that appears to be the same type as used for the processor cooling fan. The motherboard is a microATX, and the original PSU had no such black & white cable. Anybody know the funtion of this cable?

[saphalline]

That cable is rarely used. It's the rpm sensor cable for the PSU fan. Some mobo's have a header labeled "PSU_FAN" or whatever, and you can then go into the BIOS and monitor the speed of the PSU's fan along with all the other fans and temps. Some mobo's even allow you to put a warning threshold in the BIOS to go off if the PSU's fan drops below a certain speed.