[SOLVED] Should a CPU cooler fan be push or pull?

[LetsPlayThisBro]

I have a Noctua NH-U14S and I'm about to upgrade the fan to the new Chromax/black fan with black shroud to make it look much nicer. But it got me to thinking, especially because I also have a new case, should I mount the fan to push air through like I have it now and how I see most everyone do it, or should I mount it to pull air through from the other side? The fan is 150mm so it's slightly larger than the cooler/fins so I thought perhaps drawing air through might be more efficient. Thoughts? Thanks in advance.

 

[Darkbreeze]

It really doesn't matter. It would perform better with BOTH fans installed, like mine. I have a pair of NF-A14 Chromax.black.swap fans on it. I get about four degrees better temps than I did with either push or pull, however, I got the SAME temperature with only one fan in either push or pull configuration. So it really doesn't matter. Push is the preferred configuration for a single fan however, unless there are memory interference issues in which case moving it to the rear of the heatsink is fine too.

 

[Deleted member 2720853]

It really doesn't matter. It would perform better with BOTH fans installed, like mine. I have a pair of NF-A14 Chromax.black.swap fans on it. I get about four degrees better temps than I did with either push or pull, however, I got the SAME temperature with only one fan in either push or pull configuration. So it really doesn't matter. Push is the preferred configuration for a single fan however, unless there are memory interference issues in which case moving it to the rear of the heatsink is fine too.

Question, how does your NF-A14 not make that wobbly/undulating noise with those hexagonal holes in your case? I mounted the grommets, put one of those on the rear in my case, and it was still making that wooshing noise. It's annoying. My Pure Wings 2 do not make the same noise.

 

[Darkbreeze]

Not sure what the shape of the holes has to do with any abnormal noises, even though the shape does affect noise LEVELS, but my system is nearly silent except when it's under a very high load and even then it's still pretty quiet.

Make sure you have the fan oriented correctly so that it is exhausting out the back of the case and not bringing air into the case to clash with the airflow coming off the CPU cooler. Every fan in my case is an NF-A14 PWM Chromax.black.swap except the rear exhaust which is actually an even higher end NF-A14 PWM iPPC industrial 2000rpm.

Setting your fan curve correctly in the BIOS, AND making sure that the fan header is set to PWM and not Auto or DC control, can have an affect as well. Sounds to me as though you are experiencing the fan running at full speed all the time OR you have the source for that fan header set to "CPU" rather than being set to "System" or "PCH" in the fan settings of the BIOS.

Other than that, no idea what you mean. I don't hear any such noises from this, or any of the many other builds I've installed these and other fans in. When it comes to fans, Be Quiet doesn't even come close to touching Noctua as far as noise levels and performance. They are only able to achieve their low advertised noise levels by limiting the RPM of their fans to a very low RPM on most all of their fan models. Noctua and Thermalright on the other hand, invest superior engineering and thousands of hours of testing to develop fans which are able to provide low noise levels AND high CFM and static pressure operation, without having to limit the RPM to a degree that affects overall performance in order to do so.

 

[LetsPlayThisBro]

It really doesn't matter. It would perform better with BOTH fans installed, like mine. I have a pair of NF-A14 Chromax.black.swap fans on it. I get about four degrees better temps than I did with either push or pull, however, I got the SAME temperature with only one fan in either push or pull configuration. So it really doesn't matter. Push is the preferred configuration for a single fan however, unless there are memory interference issues in which case moving it to the rear of the heatsink is fine too.

I think I only have one of those wire deals to attach a fan and I have no idea how to get a second one or I'd actually do as you've done here and put a second fan on the thing. As it stands I'll just keep it in push configuration when I finally get around to installing it, in a few days I expect because I have to be ready to shut down my PC for a few days to get everything cleaned up.

I mean I have a lot of compressed air to blow out/clean everything and then wash the cooler in distilled water to avoid water spots and all that. Same for the mobo/GPU but just tapping them with a sponge to get anything off them that even resembles dust but to do that even with a lightly moist sponge I will have to keep all the parts out to dry out completely before trying to install/power things up again.

It will be nice to reapply/reseat thermal compound as it's currently set up I haven't done that for about 3 years. Anyway I'm babbling, thanks for the heads up on that, and hey if you know how I can get another of those little wire deals to get a second fan on it I'd appreciate the info.

 

[Darkbreeze]

The NH-U14S comes with an extra pair of retainer wires for adding a second fan, BUT that only works if you use a second NF-A15. If you use the NF-A14 fans you have to get different clips from Noctua and they will send them to you for free if you show them proof of having purchased both the cooler and the fans.

• NF-A15 PWM premium fan
• Low-Noise Adaptor (L.N.A.)
• NT-H1 high-grade thermal compound
• SecuFirm2™ Mounting Kit
• Anti-vibration pads and fan-clips for second NF-A15 (optional)
• Noctua Metal Case-Badge

 

[Deleted member 2720853]

Not sure what the shape of the holes has to do with any abnormal noises, even though the shape does affect noise LEVELS, but my system is nearly silent except when it's under a very high load and even then it's still pretty quiet.

Make sure you have the fan oriented correctly so that it is exhausting out the back of the case and not bringing air into the case to clash with the airflow coming off the CPU cooler. Every fan in my case is an NF-A14 PWM Chromax.black.swap except the rear exhaust which is actually an even higher end NF-A14 PWM iPPC industrial 2000rpm.

Setting your fan curve correctly in the BIOS, AND making sure that the fan header is set to PWM and not Auto or DC control, can have an affect as well. Sounds to me as though you are experiencing the fan running at full speed all the time OR you have the source for that fan header set to "CPU" rather than being set to "System" or "PCH" in the fan settings of the BIOS.

Other than that, no idea what you mean. I don't hear any such noises from this, or any of the many other builds I've installed these and other fans in. When it comes to fans, Be Quiet doesn't even come close to touching Noctua as far as noise levels and performance. They are only able to achieve their low advertised noise levels by limiting the RPM of their fans to a very low RPM on most all of their fan models. Noctua and Thermalright on the other hand, invest superior engineering and thousands of hours of testing to develop fans which are able to provide low noise levels AND high CFM and static pressure operation, without having to limit the RPM to a degree that affects overall performance in order to do so.

Yeah, already did all that. I hear this high pitched humming noise from the fans. Doesn't occur on my Pure Wings 2 without any grommets. Guess I'll just use the original fans.

 

[Darkbreeze]

Problem is likely about ten inches away from the keyboard. Those Noctua fans are just like any other fans. If the rubber screws are a problem for you, you can install them like any other fan using regular case fan screws. I've installed dozens and dozens of fans using rubber mounting screws though, and never experienced what you are talking about so I think it's either something you are doing or some other issue with your system as I said.

But since this is somebody else's thread, let's leave off the discussion of your issues here. If you wish to discuss it further then please start your own thread and I'd be happy to try and help you sort it out.

 

[LetsPlayThisBro]

The NH-U14S comes with an extra pair of retainer wires for adding a second fan, BUT that only works if you use a second NF-A15. If you use the NF-A14 fans you have to get different clips from Noctua and they will send them to you for free if you show them proof of having purchased both the cooler and the fans.

• NF-A15 PWM premium fan
• Low-Noise Adaptor (L.N.A.)
• NT-H1 high-grade thermal compound
• SecuFirm2™ Mounting Kit
• Anti-vibration pads and fan-clips for second NF-A15 (optional)
• Noctua Metal Case-Badge

The receipts will be easy but I need to dig in my closet to find the box it came in just to see if I still have the second clip, but I could swear I only always only had one. It's been years since I bought/opened it though so maybe my memory is a bit fuzzy. Thanks for the info though, I will get the second fan if I have the clip or am able to get it from Noctua.

 

[digitalgriffin]

For a solid vertical fin stack as in your NH-U14S it doesn't matter. +.1" supply water pressure has the same effect as -.1" water pressure suction from a differential standpoint. (This coming from an engineer)

Now if it was something like Wraith Spire, point the air downward. That way the air is forced over the entire surface at the base, and then fans outward to cool components like VRMs.

 

[Darkbreeze]

So you are saying that I'm not being truthful, or am I misreading your intentions? The properties of hydraulics are entirely different, with practically no similarities as those of air. Air is compressible. Hydraulic fluid, for all intents and purposes, and we'll call ANY liquid a hydraulic fluid for the sake of argument, is not.

And that might be the least of the differences. I don't believe your equation has any true relevance to the benefits provided by adding a pull fan to a heatsink, any heatsink. Engineer or not.

Not only did I see a four degree difference in core temperatures by doing nothing more than adding a second fan to the heatsink, others have seen similar results as well.

Here, they see only a two degree difference, but I've seen a lot more money spend for less gain that that in other areas.

https://www.tweaktown.com/reviews/5434/noctua-nh-u14s-cpu-cooler-review/index8.html

Other sites that tested push pull configurations tended to note anything between 1-3 degree temperature differences. The fact that I noted a four degree difference MIGHT owe the additional degree to the 2000 rpm fan at the rear exhaust which is eliminating any bottleneck on airflow from the cooler, so that the rear fan is not a hindrance to it's performance.