H115i for 5960X and for TitanX fan config, radiator placement

[orcinusdev]

Hi.

 

Can you please suggest:

 

Q1: for a 5960X at 4,2-4,7GHz should I go with a push-pull config of the fans?

 

Same question for TitanX @ 1500-1600ish Hz.

 

I'm planning on using either stocks, SP140 or some other industrial high pressure fans (like 4mm Noctuas or even higher).

 

Q2: Do I need a radiator to be above the block/pump (this renders front placement impossible, and bottom especially)?

 

I care for noise, but performance is important.

 

 

Thank you.

[c-attack]

1) You don't need push/pull on a 27mm thick 280mm radiator. Either SP140L or NF-A14 industrials are more than fan than needed and you will have more RPM range than you are willing to use. At the lowest levels (500 rpm), the push-pull will move more air through the radiator. However, you don't need it at idle and you can always run the single pair of fans just a little bit faster to equal things out. So unless you are building some sort of system where you must have very low maximum fan speeds, I don't see any advantage. Also, unless you have a monstrous case, the heatsink and top 8 pin motherboard plug often do prevent a push-pull mount on 280mm radiators.

 

2) So two H115i - one for CPU and GPU? Same as above, only more so. While there are times with low-moderate CPU load where 4xSP140L at 600 rpm could offer good cooling and low noise, the GPU needs are a little different. They are either a) idle (desktop levels) and do not require anything more than minimal fan speed; or b) running moderate speeds while gaming with a consistent GPU load. This is further complicated by where you intend to mount this radiator. In most cases it would have to be 280mm top for CPU and 280 front for GPU. Since those front fans are also responsible for all air intake, you may need to run them at a higher speed all the time to get air into the case. Now that might be a reason to run push-pull. If you are running higher front speeds all the time, the ability to lower the speed by 200 rpm might have some value. However, GPU length and 77mm of radiator fan may create an issue.

[orcinusdev]

1) You don't need push/pull on a 27mm thick 280mm radiator. Either SP140L or NF-A14 industrials are more than fan than needed and you will have more RPM range than you are willing to use. At the lowest levels (500 rpm), the push-pull will move more air through the radiator. However, you don't need it at idle and you can always run the single pair of fans just a little bit faster to equal things out. So unless you are building some sort of system where you must have very low maximum fan speeds, I don't see any advantage. Also, unless you have a monstrous case, the heatsink and top 8 pin motherboard plug often do prevent a push-pull mount on 280mm radiators.

 

2) So two H115i - one for CPU and GPU? Same as above, only more so. While there are times with low-moderate CPU load where 4xSP140L at 600 rpm could offer good cooling and low noise, the GPU needs are a little different. They are either a) idle (desktop levels) and do not require anything more than minimal fan speed; or b) running moderate speeds while gaming with a consistent GPU load. This is further complicated by where you intend to mount this radiator. In most cases it would have to be 280mm top for CPU and 280 front for GPU. Since those front fans are also responsible for all air intake, you may need to run them at a higher speed all the time to get air into the case. Now that might be a reason to run push-pull. If you are running higher front speeds all the time, the ability to lower the speed by 200 rpm might have some value. However, GPU length and 77mm of radiator fan may create an issue.

 

Thanks for this elaborate answer. So, the case will be either: Corsair 900D or InWin 909. Depends on what I'll do with it.

 

I am hunting for maximum possible silence or lowest possible noise so, if a push-pull can provide 200 RPM lower speed, that might be 600 instead of 800 or 800 instead of 1000, which does add to the noise reduction.

I've been warned of vibrations a push pull can create and actually "damage" the acoustic picture thus diminishing the lower speed effect on the noise.

 

I will probably run the card during rendering overclocked at 100% load so I need max performance at that time too. Otherwise, while gaming etc. I'll be using stock speeds when I need it silent. :)

 

Regarding fans:

 

It is still not clear to me (and probably it won't be unless I test it myself):

Are nominally faster fans less noisy on lower RPM than those where "lower RPM" is their mid or even max, like in case of Noctua Industrial 3000, 2000 and Redux 1500, 1200: pressure curves (imagined) of those fans show slight advantage to faster industrial fans, but I've found no good and clear info on the question if an Industrial Noctua at its minimum of 800 or 500 RPM (for 3000 and 2000 respectively) is at the same noise level as a Redux at that speed. Judging by logarithmic curve I can plot, it should be and it should also offer more pressure than at the same RPM running Redux model.

 

However, there are people claiming Industrials are too loud. But, then in comments on such claims one can find out someone is commenting on 100% RPM, which then invalidates comparison with a Redux at mere 1500 RPM or half the speed.

 

For example: bundled CSR SP140L are set up at 2000rpm, 104.65CFM, 40 dBA, 3.99mm H20. Industrials at 2000 RPM are set up at 182 CFM, ~4,18 mm H20 pressure and 31.5dBA, which is significant enough already to replace stock SP140L. 10 dBA s a lot.

 

Then I take a look at Industrial 3000 with even more pressure at 40dbA - 10mm pressure for the same acoustic declaration of SP140L - should, in my own theory, give much better performance when running at min 800 RPM than Industrial 2000 or SP140L at it's 2000 and 40dBA....

 

?

[c-attack]

I know static pressure is given some weight when evaluating fans for radiator use. However, you need to remember what that number really is --- the amount of pressure necessary to reduce the fan speed to zero. Imagine the crappiest, weakest fan you have ever seen. Can you picture it grinding to a stop because you slapped an air filter on in front of it? Even covering it with your hand would probably fail to stop it. The actual resistance offered by a radiator in terms of "mm of H20" is rather small. Otherwise, it would indeed stop some fans when you tried to run them at low speed. The number does give some indication of how susceptible a fan is to negative pressure, but it is still airflow that matters. Generally, I consider any fan with a static pressure less than 1.0mm H20 at maximum speed to unsuitable. Anything with more than 1.00 is possible, but air flow should then be compared. There are always exceptions and as you'll see below, the number isn't all that valuable.

 

Static pressure is extremely RPM dependent. Two fans with identical blades and frame with have the same static pressure rating at the same RPM. However, compare the two different versions of SP120 PE and QE. The 3.1 mm on the PE would seem to be an overwhelmingly better choice than the QE's paltry 1.31mm. Note the airflow as well. Of course, it's the same fan and at 1450 rpm the Performance Edition will also only move 37 cfm and push 1.31mm H20. The only thing the PE offers the QE does not is the ability to run substantially higher and louder speeds. Most people do not like their 120mm fans up in the 2000+ range, so you always need to evaluate fans within the range you are willing to use. 120mm fans in particular have a very strong "lift" in their P-Q curve in the last 100-150 rpm. Unfortunately, your noise also increases dramatically at 90%+ voltage and this range is rarely used by most people. 140mm fans have a more linear and smooth P-Q curve which makes predicting their specifications at a given RPM a little easier.

 

For example: Imaginary Fan N has both a 2000 rpm and 3000 rpm model. Same frame and blade. At 2000 RPM they both will have the same capabilities. If you are not willing to run the fan at 2000+, you gain nothing. You are likely to loose something, usually minimum RPM speed. The 2000 model may run just under 500 rpm. The 3000 may have a minimum of 800-850. 500 rpm is inaudible for most any 140mm fan. 800 is not. You lose your silent desktop work ability.