You get the most air through the fins with the hub in the center of the fin stack. You get more air over the board with the fan mounted low. In practice, the difference is usually minimal, within reason.

 

Almost zero effect if you already have good airflow from intake fans. If you mount them too low however, and they touch any metal part of the cooler, the vibrations will travel. I've done it myself. I was also under the impression that the lower part of the fan that blows air over VRM's helped cool them down, but to my surprise the temps are exactly the same using an NH-D14 and a be Quiet! Dark Rock Slim. I checked using software and the thermometer gun I used when my NH-D14 was installed. I use a Fractal Define C with 2 140mm NF-A14's PWM.

 

Not by much in my experience, if any at all. I actually had to do so in order to fit my RAM underneath the NH-D15 and a ton of fans for hardcore overclocing.
The biggest difference came from not installing a second fan altogether.

 

According to noctua the difference is only 1-2 degrees between one and two fans.

 

Sometimes mounting lower helps mobo component temps, especially if mobo components run hot.

1x in middle vs 2x fans on twin tower is same temp at same fan noise level. 2x fans are about 2db louder than 1 fan. Slow 2x fans down maybe 100rpm to same dB ans single fan and they move same mount of air.

 

My two cents: I use custom fans sometimes on cpu coolers. Not all case fans are built the same. Some cool better on the sides then directly through their fan chasis. You can also cool a very large cpu heatsink with a table top fan too.

 

Not enough to be relevant

Sent from my Redmi Note 5 using Tapatalk

 

Perhaps, but it would make sense if it is. We are talking a lot more coverage of the pipes. Most people with dual setup wants a symmetrical setup and aim for the top rubber part to be level with the top fin. Noctua themselves have it mounted 7 fins down. That is a big difference in terms of coverage.

 

I have found that the key to cooling a meaty processor is to make the heatsink fans blow air across the fins, and then make them also force air out of the case.
I am sure a test bench is good for some things but, it does not simulate real world in some ways. IE, if you have a case and it has at least a couple of 140's intake and say three 120 exhaust. That should have enough air coming in and going out, right? But, if the output from your heatsink fan is too far away from the exhaust, the hot air can circle around in the case, instead of blowing out of it.
Now, let's take 1/2/3 fans blowing hot GPU exhaust up into your CPU heatsink to compound the problem.
See, now that would never happen in a test bench. All that massive heat produced just dissipates in all directions, because it cannot get trapped.

I have a custom shroud that directs air across the South Bridge and up into the GPU. Of course the GPU moves it up into the intake (push) fan of the CPU heatsink. I wrapped the exterior of my CPU heatsink so it's heat continues to travel upward (instead of out the sides). I also created a shroud on top of the exhaust (pull) fan to connect it to the top of the case. I also created a shroud to direct the heat from my VRM into the rear exhaust 120MM.
On both cases, I have fan controllers (NZXT) and the net effect is lower fan speeds (quiet fans in most locations), and the shrouding muffles the noisy Z axis dual ball bearing heatsink exhaust (pull) fan that does most of the heavy lifting. IE, pulls heat out of the SB, GPU and CPU, then forces it out of the case.
Oh, and MX-4 paste continues to blow my skirt up!
I have tried a lot of fixes. Sometimes you can do something silly like remove a dust filter and your temps drop enough to make your pulse race.
But, this the way I cool my two 4GHZ systems (limited in BIOS to save energy and dump less heat into my office).
And, since both of these machines are within two feet of my ears, on my desk, it makes the whole smack quieter too. Happy Cooling!

 

I have found that the key to cooling a meaty processor is to make the heatsink fans blow air across the fins, and then make them also force air out of the case.
I am sure a test bench is good for some things but, it does not simulate real world in some ways. IE, if you have a case and it has at least a couple of 140's intake and say three 120 exhaust. That should have enough air coming in and going out, right? But, if the output from your heatsink fan is too far away from the exhaust, the hot air can circle around in the case, instead of blowing out of it.

There's a better way of doing that and preventing air circulation.. Have a massive intake with little resistance and passive exhaust. It's basically like flooding a tank with a tube that moves the tank volume at least once per second.

Say for example, lian li 215 with 3x140 in front, 1x140 bottom, top sealed and back open. It's a 45L case.
Let's take for example nf a14. At 1500rpm it's rated by noctua at 140m3/h. Turning that in l/s results in 38,9L/s x4, it's 155,5L/s. Drop them down to 1100rpm and account for case resistance and inneficiencies, you're still left at 60-70L/s..................

 

What Shawnb99 said.

Changing cooler fan location does way more than just change how air flows thru cooler.

It also changes airflow above / below / arround cooler thus changing case airflow . When case airflow changes temp of air entering cooler changes as well. This means temperature of air entering cooler changes when fans are moved. Any change in air temp entering cooler changes CPU temp by almost exactly the same amount .. it's a 1:1 ratio of change between air entering cooler and CPU temp. This means when air temperature entering cooler changes CPU temp also changes by the same amount (with CPU at same load and fan speed).

If you move fans on cooler you not only change how air is flowing thru cooler but also how air is flowing thru your case .. thus changing air temp entering cooler and changing CPU temp even if cooler is flowing same amount of air on a different path thru cooler.

So in a case built system you need to be monitoring air temp entering cooler as well as CPU temp to know if changing cooler fan location is really changing cooler's cooling ability.

Hope that's not too confusing.

 

Changing cooler fan location does way more than just change how air flows thru cooler.

Interesting... (click image for the review)

 

IME, the only advantage of the first image configuration is it pulls air across the RAM, cooling it. And it does make a difference there, especially for overclocked RAM.

 

I run a 140 and 120 on my twin stack cooler. I do have the 120 elevated for two reasons. 1, to make room for airflow coming off the front fans to make it to the memory, and 2, That roughly 1/4" elevation means the center 140mm fan gets a little more fresh air than it normally would. I could use a 140 fan in the front position, but it would look ridiculous.

 

Pictus, sorry, I don't understand what your "interesting" statement means in reference to quoting my post. Could you please explain?

What Shenhua said about image Pictus posted.

We need to know how testing was done to determine if results are "interesting" or not.

Pictus, could you post link to review? And do you speak the Asian language review is in?

Maybe use OCR to copy text from image, then use translator for language we know .. preferably English as that's forum language.

 

Pictus, could you post link to review?

@Pictus already did. Click the picture.