Air flow help...Postive? Negative? Neutral?

I've provided a picture of my current fan setup. Any advice and/or suggestions would be great.

I've provided a picture of my current fan setup. Any advice and/or suggestions would be great.

 

I've found marginally negative gives best cooling performance.

 

Positive pressure is difficult to achieve unless all your fans line up front/bottom to top/back. Also turbulence is a greater problem with positive pressure.

 

The ideal scenario is to have airflow in = airflow out.

 

If your have any restrictions of space you need a high static pressure fan over traditional airflow fans (SP over AF).

 

Positive pressure I found also had heat (hot air) coming out of other gaps next to components and it just didn't find it worked as well as the traditional setup.

 

You make sure you have good filters for inlets that do not restrict air flow (by being too flush with the fan itself).

I don't think you will get any better than that with that case.

 

You could try the top fans inlet/outlet setup.

 

But you've got lots of air coming in and all being sucked out the back.

 

The issue is you may get pockets of hot air forming. Which is why I said try the top fans for out rather than current.

 

As you might be putting too much faith on the push/pull radiator fans to suck all that air out.

EDIT.

 

You have your STATIC PRESSURE and AIRFLOW radiator fans the wrong way around.

 

Airflow should have no air restrictions where it is pulling air from.

 

That currently is flush against the radiator. So its restricted.

 

 

The static pressure fan should be pulling air through the radiator. As its designed to work with an air restriction.

Static pressure is cumulative between paired fans, so putting the SP120 with AF120 on the radiator is far from disastrous. That said, if the colors work for you, I would probably switch the SP120 front/top intake with the AF120 on the rear. The SP120 LED fans are really a hybrid airflow/static pressure fan, unlike say the performance edition of the SP120 (colored ring version or the SP120L grey that came with your H80i). This is a good thing for most people on the case, since it provides a bit more focused flow without sacrificing a ton of CFM. You are going to get the focused flow from the AF120 in front anyway, since it sits between the HDD and optical drive cages. SP vs AF won't matter much for the bottom front fan either. If the cage is full, air isn't going to pass through no matter what kind of fan you put on it. The idea is to force air in between the drives for cooling, and really any kind of fan will work unless you are running something that keeps a stack of drives active for a very long duration. Still, I wouldn't switch the lower front fan unless it's convenient. You are not likely to get a performance increase of any kind between AF or SP120 LED.

 

Don't get carried away with positive vs negative pressure. It's one thing in theory, but in reality your calculations rarely work out. People run their numbers based on the max specifications of their fans. Trouble is, you rarely run all your fans maxed out. H80i fans will be set to CPU temp. Front intakes you might set to high. Top fans, probably not so much. And then there is resistance. You don't get 57cfm from your SP120 placed against the radiator. You will get less because of the restriction. Nor do you get the full spec numbers from any of your fans because they all face some sort of resistance whether it's a fan filter or just the case and environmental pressure. So how much air do they move? Can't tell you and neither can anyone else without some serious measuring equipment. Changing variables, unknown air flow values -- you are just making rough estimates not scientific calculations.

 

If you want to keep dust out, get your case off the floor (which it looks like you have already done) and get a front air filter - least restrictive possible. Anything beyond that is small potatoes. If you want to keep a positive pressure environment at desktop work levels, run your front fans at a moderate speed and everything else low. When under load, you need to think about system health not dust particles, which are just as happy to stick to your RAM as their are to blow out the back of the case.

 

You probably do want to consider flipping your top fans around to exhaust. In your current set-up, all of your exhaust heat is being funneled through the H80i. The problem with this is two things:

 

1) The H80i fans will be set to run at whatever speed the CPU temp requires, not maximal exhaust. This means you exhaust capabilities will be low at best unless your CPU happens to be running hot. Additionally, even at max speed you may only be able to move 40-45CFM through the radiator --- at most. That is a pretty strong imbalance between intake and exhaust. To boot, whatever fans you put on the radiator will be the loudest in the case because of the resistance. No need to blast the rad fans unless you need to do so.

 

2) SLI set-up. Those 2 GPU's are the biggest source of heat in your system. Blower design or not, they will still radiate substantial heat up. This is then being pushed through the H80i radiator as your "cool" intake air to carry the heat from the water out of the system. Your CPU temps will be higher than a bench test of any h80i because of that warm air. This isn't necessarily a problem, because for most people they have relative low CPU loads in conjunction with higher GPU loads, like most modern games. Using the top fans as exhaust would lift a large burden from the H80i and getting the GPU heat out of the system should be priority number 1. If you have some CPU intensive work that needs to be done, then we may need to talk about a different configuration.

Thank you all for the advice. I'll try the top fans as exhaust and check the temp differences. As for the SP120 on the top/front, should I swap it with the AF120 that's at the very bottom? I went with the SP120 in Push and the AF120 in Pull on the Rad after watching a LinusTechTips video on push/pull. I'd agree with the dual SP120s on the Rad as that's how it comes stock, but I wasn't knowledgeable about airflow at all and just went with Linus' benchmarks.

Whoops. Totally missed the bottom fan with my cropped window. That one is fine too.

 

I may have been ambiguous in my wording. I would take the one of your SP120 LED's from the front of case and switch it with the AF120 in pull on the radiator. (Run two SP120 LED's on the rad). If it ruins your color scheme, don't worry about it. We are probably taking about a 2C avg core temp difference during an hour of gaming. You could stretch the difference out a little more on a full CPU stress test, but if you don't run any programs that apply loads in a similar fashion, I don't see the point in worrying about a condition that will never exist.

 

As for the radiator, resistance is resistance, it doesn't matter which side it's on. If you have a 100lb block on the floor, it takes that much force to push it or to pull it. It doesn't matter the direction you apply the force from. Same thing with the fans on the radiator. Resistance in front or back of the fan is same, either way. The only reason I might use an air flow fan in the pull position would be to experiment in changing the tone of the fan noise. (Pull fans can make a little more noise in the way they interact with the case grill and turbulent air entering the fan). That's getting into the neurotic audiophile territory where I live, so for normal people there is no advantage. Also, unlike static pressure, air flow (CFM) does not stack between pairs of fans. So if you have a 50 cfm fan in push and a 40 cfm fan in pull, you will never get more than 50 cfm. That's the theoretical maximum. In reality, you'll get less than that because of the resistance provided by the radiator and even the other fan itself. The advantage of push/pull is overcoming a very large resistance in a thick/dense radiator or the freedom to use two low static pressure fans, without sacrificing a ton of air flow and possibly creating less noise. Ultimately, it's the amount of air being pushed through the radiator that does the job -- not whether someone markets the fan as high airflow or high static pressure.

 

All of that stuff is minor tweaking. Setting the two top fans to exhaust I would consider more crucial. You likely won't see large differences in GPU or CPU temps (unless under long load). Look to motherboard and PCH temps to get a better handle on what the ambient temperature is inside the case. Some of the Asus boards have temp probes you can use, but not all.

Ok, so...top fans to exhaust. Swap the SP top/front fan with AF fan on the rad. I'll also post a photo of the front of my case Tuesday, since I cut open the front panel and added a filter for more airflow.

There is some debate on which way to set psu, but if you still have heat issues, you could try and flip the psu around if the case allows it so it sucks air out of case, I think it helps pull heat away from the gpus when they are active.

Here's front of the case. I've rotated the top fans to exhaust and swapped the AF120 from the Pull position on the rad with the SP120 from the Top/Front. Now running dual SP120s on the rad in Push/Pull. Thanks again for all the help.

From a glance, I'd replace that top static pressure fan intake in the front with an airflow fan. Static pressure fans generally perform best on radiators or with some kind of obstruction of airflow in front of it (like a HDD cage). Your top front intake fan has a straight line of sight to your GPU with no real obstruction in the way. I'd personally replace that fan with an airflow fan so you get more CFMs and cool air onto your GPU.

That was post #10, although in this case it was done for the benefit of the H80i. In the LED 120mm package, AF vs SP airflow differences are small and the SP is really more of a general use hybrid fan than a serious static pressure model like the SP120 PE.

Herers my fan setup just for comparison

 

http://i.imgur.com/bnkJRYf.jpg?2

EDIT.

 

You have your STATIC PRESSURE and AIRFLOW radiator fans the wrong way around.

 

Airflow should have no air restrictions where it is pulling air from.

 

That currently is flush against the radiator. So its restricted.

 

 

The static pressure fan should be pulling air through the radiator. As its designed to work with an air restriction.

 

no thats wrong

on static pressure fans. the intake side is LOW pressure. it has to hit the blades and be compressed against the housing to achieve the higher pressure and airspeed (Im a mechanic and study Turbo geometry trust me)

its a good setup like this . I mean even the air flow fan on the outlet of the radiator could be a high static pressure model as well. But I understand his rationale of having an airflow optimized version here.

for more air volume