I had an old case fan which I wanted to change in my Sonata Case because I had changed the PSU and the fan was spinning loudly at 100% all the time ...

I first had an E6750 with the stock Intel Fan plugged into the CPU_FAN header, using smart fan to PWM in bios. Worked flawlessly.

Now to replace the old system (case) fan, I bought that PWM Artic Cooler 12PWM. I had tried to do some research about the SYS-FAN2 4-pin header on the mobo, but as there was limited litterature, I took a chance and hoped that a PWM fan would work and regulate itself according to system temperature (not cpu) when plugged to SYSFAN2, even though in BIOS there is no option for System Smart Fan Control.

But when plugged to SYS-FAN2 header, the PWM-type fan does not spin at all.

THEN, and only then, I used the Arctic Cooler PWM sharing technology and now BOTH the CPU and CASE fans are plugged together in the CPU_FAN header and BOTH fans regulate themselves based on the CPU temperature. Temperatures are fine (I think) and within normal ranges for CPU and system. Everything works, but I only wonder the following :

What is the purpose of having a 4-pin header SYS_FAN2 if you can't use the PWM 4-pin fans???? I noticed that in manuals for other motherboards, there is such a thing that specifies PWM as smart fan control for a system (case) fan, which we do not have that in the GA-P35-DS3L bios.

Do I need an external program to control the case fan? Is it even possible or that 4-pin header is just there to look pretty?

And is my current setup safe? (PWM sharing) ? Thanks, I'm counting on you!!!