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What’s the difference between the CPU FAN” socket, CPU OPT socket, and the SYS FAN socket on motherboard?

What’s the difference between the CPU FAN” socket, CPU OPT socket, and the SYS FAN socket on motherboard?

A CPU FAN header does exactly as it says on the tin. A normal PC would have a sole CPU and a heatsink with a fan positioned on top of it. That is where the fan would be plugged in.

That header is significant because it detects whether or not your fan is operating. If it detects that the fan is not functioning or is not functioning correctly, it will shut (or refuse to start) your system to prevent the CPU from overheating.

CPU OPT is a shorthand for CPU optional. This is frequently the header to which some type of wire for a vapor compression refrigeration system is attached.

SYS FAN is known by several different names. Asus calls them chassis fans or CHA-FAN. Other motherboards have referred to them all as case fans. Whatever you call it, these are all the headers that allow you to connect the fans that cool your enclosures or case.

Let’s explore these terms!

On the B550 DS3H, where is the CPU OPT?

There is no CPU OPT fan header on the Gigabyte motherboards to power additional conditioning on the DS3H series. However, there are two SYS FAN headers.

If they’re already in use, you can obtain a cable splitter that utilizes a single fan header to share power between two fans (though I wouldn’t use it to run liquid conditioning), or you can get either a 4-pin Molex LP4 to 3-pin TX3 adaptor and attach the fan connected to the power supply.

The disadvantage of directly powering from the PSU is that whatever is running from the Molex adapter will most likely be operating properly speed, rather than using PWM to regulate the fan speeds dependent on your BIOS settings/heat.

As a result, fans or water pumps would be running at full speed and would be quite noisy. Because all of the fan connections on the DS3H series support PWM, you’d be better off using one of the SYS FAN headers unless you also need to power several fans in the computer case.

Is it possible to connect a CPU cooling unit to the CPU Opt if that is the only fan?

You certainly can.

Regardless of their intended usage, CPU FAN and CPU OPT are fundamentally the very same thing – they are PWM headers.

The documentation instructs you to attach your cooler fan to CPU FAN since the BIOS is set to manage the speed of CPU FAN based on the CPU temperature sensor by default, and you should anticipate upgrades to the BIOS to do the same.

CPU OPT, on the other hand, may not be set up that way by default, thus if you just had one fan connected to OPT, you may start the system without a fan going. As a result, the manual is cautious and instructs you to link to CPU FAN.

What should I do with my case fans?

Attach case fans to the motherboards, beginning with the CPU FAN label on your motherboard and working your way down to your CPU fan. This is significant since your BIOS often monitors CPU fan speeds and may prohibit the computer from starting if a CPU fan is not recognized.

Does the orientation of a CPU cooler fan (facing RAM or not) matter?

As far as RAM is concerned, no. DRAM is already extremely low power and, as a result, may be cooled passively. Actually, the expensive heatsinks on DIMMs don’t accomplish much either. So don’t be concerned about DRAM cooling.

Your overarching objective should be to avoid disrupting the existing airflow (from case input to case output), therefore directing your cooler fan toward the exhaust.

What are some CPU fan alternatives?

If you don’t want to use fans, the best solution is to open it up and install a huge heat sink.

However, with today’s CPUs, this is not feasible. Even if you are able to do so, some air movement will be required.

As a result, the most feasible option is to employ an All-In-One (AIO) CPU water cooling system.

These employ 1 or 2 fans at considerably slower speeds (and hence much less noise) in conjunction with radiators and a tiny water block that sits on top of the CPU. This technique works quite effectively and has a low risk of leaking. 

In Case You Need A Quick Fix For A Broken CPU Fan

Why would someone want to manually manage their computer’s fan speed?

Except in exceptional cases, their computer has numerous fans, and having them all operating is unnecessary.

One of their fans has broken or is too noisy, and they wish to lower the speed of one while boosting the speed of another.
A firmware or thermal sensor issue is forcing the fans to operate at full power all of the time. It’s a good idea to reduce them by hand. You want to put the supporters to the test.

Is it possible to plug a CPU fan into a SYS fan slot?

It is possible, but it will not work correctly since there are much more controls over the speed, and it may impair the performance of your cooler, affecting the operation of the CPU. There ought to be a fan header near the socket labeled CPU FAN or something similar, to which the CPU should be attached. If you can’t see it visually, consult your motherboard manual.

Final thoughts

CPU FAN is the primary fan connection for the CPU cooler. Because some coolers have two fans (one push and one pull), the CPU OPT supports the addition of a second fan.

SYS FAN might be any of the fans in the container that you want to connect to the motherboard and monitor using the BIOS.

For the detailed yet shortened version of this article, click here.

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