Does my CPU need PWM fans?

[Deleted member 44897]

Six months ago, when I built this microATX PC, I installed PWM fans throughout. But this week, I swapped the PWM case fans out for standard ones.

The reason being is that the fans would stir up and down constantly (all of them), even during mundane tasks. They work fine, but the constant ramping up was annoying. These regular fans are only a few decibels louder than my others, but I like this much better.

The fans in question are all Cooler Master: 92mm x2 (CPU) on a Cryorig m9i heat sink, 1 80mm (rear), and 2 120mm (front and top).

The CPU has always been stable at an average of 30C. However, this is the first time I've used PWM fans, and I am seriously intent on going back to standard. I don't do anything graphics or CPU-intensive to warrant a hard spin on my fans.

My question to you all is: does my CPU need PWM's, or am I okay going back to standard fans?

I may be overthinking this, because I do believe I've been using standard fans all along until now. Any information would be appreciated. Thanks!

 

[Mojazz]

Nothing wrong with standard fans. They provide their maximum cooling all the time. PWM is great for noise reduction. If your standard fans spinning all the time at maximum rpm do not bother you audibly, stick with that solution. It will provide max temp control.

 

[TMTOWTSAC]

The short answer is you can use whatever fans you like as long as they're keeping up with temps.

A longer answer is that you should be able to set a custom fan curve to control the speed of your PWM fans. Check your BIOS to see what fan profiles are built-in, there's probably already one in there that suits your needs.

 

[Paperdoc]

Both 3-pin (older) and 4-pin (new PWM) fan types do just as well for air flow. The difference between them mainly is in the METHOD the mobo header needs to use in order to control the fans.

Most mobos now can use either fan type on the CPU chip cooler, and many actually claim to automatically detect which fan type is connected and adjust themselves so that they CAN control the speed of either fan type. That is not guaranteed for case ventilation fan headers. Some can control only the PWM type, and will have an older 3-pin fan type run full speed all the time. Others CAN control the speeds of both fan types, although on some you must configure the header's mode manually in BIOS Setup. I don't know what mobo you have, so I can't tell you which type of headers you have.

 

[photonboy]

*Your main issue appears to be NOISE. You want to get the motherboard FAN SOFTWARE from the motherboard site, then optimize the profile for your CPU and case fans.

In general, case fans have rapidly diminishing returns above 600RPM or so but it varies. The CPU should be optimized based on temperature. Most modern Intel CPU's have optimal life if they don't run above 75degC very often, but frankly 80degC is fine for Intel at the high end.

If RPM varies too much, then simply raise the MINIMUM RPM to say 50% max RPM, then ramp up such that you don't exceed 80degC in a demanding, real-world task like HANDBRAKE using about 100% CPU usage for at least ten minutes.

OTHER:
1) The CPU_FAN or CASE_FAN header must support both 3-pin and 4-pin fans to use properly. It's probably the case, but just want to be clear.

2) The fan must be of variable design. (i.e. 500RPM to 1800RPM, and not something like 1000RPM plus/minus 10%)

3) PWM vs Voltage - Pretty sure there is NO difference in noise here. I believe it's solely about power consumption. I'm possibly wrong but I thought most fan noise was due to the blades' interaction with the air. (and things like bearings which are on both types of fans)... not sure that the actual magnetic interaction adds any noise?

4) Fan DESIGN - this is where EFFICIENCY (noise vs cooling) comes in. You can take a good NOCTUA fan and replace the fan on a cheaper cooler and get a quieter experience with the same cooling (or better cooling at same noise level).

That's what I did with the Cooler Master Hyper 212 EVO.

SUMMARY:
Your main issue appears to be actually CONTROLLING the fans. Again, keep the fans as SLOW as possible while still keeping the temperature below 80degC worst-case on the high end, and keep it as slow as possible on the low end too.

Again, if you idle and open open a few programs and the CPU fan is fluctuating a lot, simply raise the RPM value from say 20% to as high as 50% (I can't predict) such that the fan will stay constant until it is under much heavier load.

 

[Deleted member 44897]

Thank you for all the useful information, folks.

For reference, I have an Asus Maximus VIII GENE Micro-ATX motherboard housing an Intel i6700K CPU.

As stated before, I do believe through all the years I've been building computers, I've been using standard CPU fans. But on this build, having implemented PWM fans has perhaps caused me to become all too watchful of my fans speeds for a PC in which I do average-intensity work.

Meaning, I really don't do anything intensive enough to stress the CPU. So, considering my CPU averages 30C, would I be safe swapping out those PWM's with a pair of Cooler Masters (1900RPM's)? I would assume I could.

Frankly, I would rather have a consistent low noise fan than a quieter one that ramps up and down all the time. It just annoys me.

Thanks again!