Hi everyone I have an ASUS P8Z77-V LK who have 1 CPU 4-PIN and 3 chassis 4-pin. In the manual (p.2-22) the 4th pin in layout as "CPU/CHASSIS PWM" and ASUS support claim to have pwm header. I found weird thing that happen when I connect a pwm fan in the chassis 4-pin header that I don't have when I connect this same fan to the cpu header.
First, I test 2 Noctua NF-A14 pwm + 2 RMA Noctua NF-A14 PWM in the same test. when the noctua fan are connected to the CPU header the fan work as expect with the silence expect from noctua fan when running at less than 500 rpm. they also start to spin reliably and stay at his lowest rpm each time as a pwm fan should and they run at 300 rpm@20% with or without a low noise adapter as the spec tell us on the noctua's box. When I connect the fan to a chassis header it's a different story, the fan header can't run lower than 40% with fan xpert+ so without a low noise adapter the fan minimum speed is 600 rpm which is too loud for idle load and I didn't buy this fan because it can run at 1500 rpm, but rather to be able to run it at 300 rpm. so I have no choice to run the fan with the low noise adapter which make it run at 300 rpm at 40% but it can't start the fan at 40% on the chassis. I have to put it between 45-60% to make it start then I can reduce to 40% and it spin lower until after (5min-2h) it stop spinning by itself. Another clue is that when they spin below 400 rpm they make a ticking noise and a whoopping noise also that is not present on the CPU header. The last clue is that when I plug 2 fan on the same header on the chassis header the 2 noctua run at about 100 rpm at 40% with an even louder noise before they stop after a random time, on the CPU header hey run at 300 rpm at 20%. I didn't found a limit or current for the chassis header but the noctua shouldn't exceet this limit because they only take 0.13A each. The CPU header is label at 1A of max current.
So, with all those weird thing that sould happen with a voltage controle header (3-pin mode) Asus think that it is a RMA case, but do you think that my motherboard really has a defect on all chassis header but not on the cpu header? do you think that it is design this way on the chassis header to run in dc mode even if the 4th pin is label as pwm? Is it worth paying the shipping to their test center or is it just wasting of money (if it's a design problem rather than a random defect)
i'll put below the recording of the fan when connected with the chassis headerhttps://soundcloud.com/kevenbastien123/ ... -pwm-noise