2 CPU Fans - Diff/Same Speed

[MrN1ce9uy]

I just added a second fan to my Cryorig H7 and they always seem to be about 100-250rpm (avg 115rpm) apart. Is this normal? They are both the same QF120 Balance fan from Cryorig.

I have a GA-Z97X-Gaming 7 and have the second fan plugged in to the "CPU_OPT" next to the "CPU_FAN".

 

[Tanyac]

If you are running a cooler with two fans you actually want the fans to be the same speed. If not, you want the pull fan to be running faster than the push fan, otherwise you might get some blow-back. I don't expect this will be a major issue @ 115 rpm.

Personally, running two fans on the cooler I would connect to the CPU_FAN header with a splitter cable. But that's personal choice.

On some BIOSs it possible to set CPU_FAN and CPU_OPT temps/voltages independently. One reason why it's better to use both fans off one header; they will both be controlled the same.

just my 2c worth.

 

[MrN1ce9uy]

Well it is the CPU_OPT (pull) that is faster than the CPU_FAN(push), so it should be okay? Is that by design? They run anywhere from 300-1600rpm.

 

[Tanyac]

If you're not using software to control the fans then it's likely that the motherboard is controlling the fan speeds. It is not uncommon for the CPU_FAN and CPU_OPT to run at differing speeds. They are independently controlled.

Often, you can set the temp source as motherboard or cpu. If that setting were different for these headers then it is highly likely they would spin at different speeds, since their measurement sources are different.

As I said though, I think you'd be better off running the two fans from the one header using a splitter. Then they are both controlled by the same source.