Question New fan had 4-pin option but I bought the 3-pin. Can I convert it to 4-pin to take advantage of 4-pin PWM motherboard ?

[Moonpreacher]

So here goes a VERY dumb question. I´m replacing my old 9 years MSI board for a cheap MUCAI X99 P4 + Xeon E5 2680 V3 +16gb DDR4 because my old board has been crashing for 2 years, some days doesn´t crash at all, others is a pain in the a@@ to start so, for that price ( about 80 USD ), I think is a better idea to upgrade as I just use the PC for internet ( not gaming, not watching movies ) and some light DTP homework, I even have only a fanless MSI 2gb graphic card, something that probably is completely unaceptable for any gaming reader 😛. I´m not an expert, I assembled myself the old rig. And now I have to buy a new PSU because this one doesn´t even get a signal due to being 8 Pin.😆

Anyway, also bought a 3 pin unbranded double sided fan because mobo seller said contact was 1* cfan +-3* sfan. Didn´t knew that means 4 pin ( by know you allready noted I´m a noob stuck on 10 years old technology )! The difference of price of 3 pin to 4 pin, same model was just 1 euro! It was not because of price but specifications. I know I can use 3 pin in 4 pin perfectely. Seems to me the only different part is the pin connection, I´m not going to replace for another just because of that but if I have a 4 pin mobo I also assume I could and should take advantage of PWM. Even if I´m not pushing CPU too far with the kind of use I give my PC, any advantage like better cooling or automatic power handling is welcomed as a extra. So, the dumb question is: can I put a 3 pin male to 4 pin female adapter or is there any way I can plug a molex to the reserved fourth pin, or those are just like "placebos" that doesn´t do anything than just work as an extension ( so no PWM at all) ? Thanks in advance ( stop laughing 😛 )

 

[Paperdoc]

4-pin PWM fans are a different design from the older 3-pin type, but were designed with as much backward compatibility as possible to make it easier to use in an established environment. So you CAN plug any 3- OR 4-pin fan into any 3- OR 4-pin header. If fan type matches header type everything works as expected. If you mis-match there is one way that has a limit, and that is what you will encounter.

If you plug a 4-pin fan into a 3-pin header, the fan will operate properly including speed control by the header - technically not quite optimal, but it does work well. YOUR case is plugging a 3-pin fan into a 4-pin header. The fan WILL work, BUT you will not be able to control its speed this way - it will always run full speed. You get lots of cooling (maybe more than needed), but no way to reduce the fan speed.

On most modern mobos all the headers have 4 pins. However, in BIOS Setup you get an option for most such headers to set whether the header uses the new 4-pin PWM Mode, or instead changes to behave exactly as an older 3-pin header. However, NOT ALL mobos do this, and I suspect strongly that yours does NOT offer such options for any 4-pin headers you have. On the other hand, many mobos like yours use 3-pin headers for SYS_FAN headers, and this type can ONLY behave in the older 3-pin Mode. SYS_FAN headers are the ones to use for CASE VENT fans. The CPU_FAN header is for the CPU chip cooler.