Trying to do some research on this, is it generally ok to run 2x 120mm fans off one 4 pin motherboard connector? Some say yes, it's fine. Some say you shouldn't because if you draw too many amps it's not possible to fix. The 4th pin allows me to control fan speed profiles in the bios so I can run it cool and quiet which is a huge bonus. If this would be too much current then 12v from the psu is an option - can I tap into the 4 unused pins in the cpu power cable? Could I add a resistor to slow the fans? ---------------- Waffle, don't read: The lady is having some non-specific random shut downs... bit hard to diagnose the machine because I've been unable to replicate said issue. I'm assuming it is an overheating problem because it happens when gaming. Basically I'm just looking for an elegant solution to this. Adding some extra fans in the right places seems to be my best bet. The gpu vents hot air into the case (and onto another heatsink, possibly northbridge) so placing a fan at the bottom of the case blowing air up towards the gpu might be my best bet. The cpu heatsink seems to be walled off on one side by unnecessarily large RAM modules and on the other side by the IO connectors, so either an exhaust fan next to it or another intake fan above it might provide some additional cooling.
I run two SP120s from a single motherboard header on my Z97 sabertooth without any issues. It controls them just as well as the single fans attached to the other headers
Wow, quick resonse, thanks! Just realised my fans are 3pin so the PWM is kind of a moot point Although I did find a fan speed controller and an EPS socket, is taking power from unused EPS plugs a bad idea?
Nope, I desoldered an eps plug from an old mobo and soldered it onto an old fan. Don't want to try it out just in case it destabalises the cpu voltage or something and messes up the cpu since iirc it's on the same rail.
I use PWM splitter with PSU power connector all the time. Everything I build has PWM case fans controlled by PWM signal from either CPU fan header or GPU fan header and powered by PSU. Be careful. Very, very, very few motherboards have PWM on any fan header but the CPU fan header. Several will even have the pin-out in manual showing headers' 4th pin as PWM when they are not. The only way to be sure is to use a PSU powered PWM spltter and PWM fan to test them.
Typically you are fine up to 1A current pulled from a single fan connector, and some boards could handle even more. So look up your fan current rating, divide 1A with that number and you will get the maximum number of fans on single connector .
