New Air 540 Configuration

Hi everyone,

I know a lot of forums have had pages dedicated to the 540 and the best way to optimise its cooling potential. I'm just about to begin my first ever full build, using the 540, and I've been trying to work out for myself an optimal solution to this question. Just to be clear about my needs: I'm not overclocking my 4790k yet, and I'm also installing just a single GTX 970, so I'm aware that the 540's base configuration should more than suit my cooling needs. Also, I've ordered a set of 540 magnetic dust filters from DEMCiflex, so I'm not as worried about creating positive air pressure inside as I would have been without them. So basically I'm creating this post because of two things. First, the perfectionist (or maybe that's OCD...) in me is simply curious about what is the best possible cooling configuration that I could create. Second, I want to HAVE that best possible configuration set up so that it is ready for any future upgrades/overclocking.

There is one possible configuration that I thought up today, which I haven't seen suggested or displayed in any forums yet. I've got a H100i cooler ready to go (again, thinking forward towards future overclocking), and I'm considering installing it in the top two FRONT 120mm slots, acting as intakes. I was then also thinking of purchasing an additional 120mm fan to sit in the lowest front slot (assuming this is possible in conjunction with the H100i?), unobstructed by the H100i radiator and blowing cool air directly underneath my GPU.

I would have moved the two 140mm fans that came installed in the front to the TOP of the case, as exhausts, and leave the rear 140mm as an exhaust as well. The only downside I can see is the potential for negative air pressure, but if the custom made filters over every vent work as advertised, then surely I wouldn't need to worry too much about this? Or would I be better off leaving out one or both of the top fans entirely?

If there are any drawbacks, false assumptions, better suggestions, or aspects of my plan that I'm over thinking, then I'd greatly appreciate any feedback. Like I said, this is my first full build, so I'll be grateful for any advice from those who have been at it a lot longer than me. Thanks to anyone kind enough to humour my curiosity by reading and/or replying to my post!

Best wishes to all,

Tipp Red

Even with a 970, you won't be able to run push/pull on the front mounted radiator. Possible not an issue for CPU cooling, but the radiator does create a restriction on your front intake. I pondered this for quite a while when putting mine together and originally envisioned a front mounted radiator. I'm glad I went the more traditional direction of the top mounted (280mm). One 540's biggest design pluses has to be a the unobstructed free flow of air from back to front. Temperatures on my set-up have been trivial. I am not sure my motherboard has ever made it past 23C. I just finished about two hours of play and when I opened the door to take a measurement, the internal air is cold - everywhere. Incidentally, it's about 46 mm from the end of my front 120x25mm fan to the very end of my Strix 970. Not enough for push-pull with 25mm thick fans and a 27mm rad. Slim 20mm thick fans might work, but there aren't many choices. The division between the two lower 120mm fans (where your rad would start) is dead on even with the top line of the 970. Even with the 240 rad in the top two slots, there may be a clearance issue on push-pull and I'm a little worried about the hoses on the rad. Turned so they are at the bottom may create an issue with the GPU, but looking at mine that might be more viable that the top position. A 27mm rad plus 25mm fan will be nearly flush with a top mounted 140mm fan.

It can work, but what's the foundation for avoiding the traditional top mount? Fan vibrations? Aesthetics? My rationale was I needed to have a fresh air intake to cool all the cores in my 5820k. That turned out to be the laugher of the year. With a moderate 4.2 OC, my rad fans turn at the minimum all day and the CPU never breaks a sweat, or specifically 45C. 4790K is certainly a different chip, but you may not need to over-complicate things. Regardless of CPU, with either 2x140 front (or 3x120), and H110 in the roof and a 140mm rear, I get zero heat bleed into the rad from my SLI configuration. CPU temps are the same on a CPU only run and a full power test with both cards at full load. I do attribute that to the free flowing air through the lower half of the case.

Many thanks for the detailed reply c-attack. It's great to hear a first hand endorsement of the Air 540's airflow, so I can be reassured that this problem is more of an academically interesting one to me, than one which is going to mean the life or death of my most expensive components!

Just to clarify one thing, I wasn't thinking of push/pull configuration with the rad at the front of the case. My idea was to line up three 120mm intake fans there (top two static, lower one airflow), and then attach the H100i radiator to the back of the upper two fans. I know that the rad would reduce the intake through its own two static fans, hence why I thought up the idea of the third (unobstructed) airflow fan underneath. Would that still result in an insufficient intake for the case do you think?

To answer your question about my reasons for avoiding the top mount in this possible configuration, there were a couple of reasons. I know Corsair stresses a lot that their best recommendation for the H100i is for it to be used as an intake. If the H100i is top mounted as an intake, it's going to be taking in cold air from above, heating it, and then pushing it down into the case. Not only does that run against basic thermodynamics, it is also going to mess with the 540's natural airflow path (and judging by your post, that airflow is something I'd be best advised to leave alone!). Secondly, if the H100i is used as a top mounted exhaust, I figured that it is going to be relying on air that has already been warmed by both the GPU and Mobo. However, if you've got an SLI configuration and even that isn't having a significant temperature impact on your top mounted rad, then I guess I really shouldn't need to worry too much about what effect my single GTX 970 will have!

I might experiment a bit for curiosity's sake when my 540 finally arrives tomorrow, but I'm now influenced more towards the traditional config of leaving the 140mm front intakes alone and mounting the H100i as a top exhaust.

Incidentally, if the H100i is used as an intake with one pair of decent SP120s, would the best results come from putting the fans in front of or behind the rad? I know the paper documentation shows to install the fans underneath a top mounted rad, but Corsair's online installation blog suggests installing the fans on top:

"If your system is already set up to have sufficient exhaust, then you can experiment with mounting the fans on top of the radiator where they can push cooler air from outside of the case down through the radiator."

http://www.corsair.com/en/blog/2013/february/how-to-install-the-hydro-series-h100i-cpu-cooler

Yes, I wouldn't put my radiator on the top either, if I were determined to use the H100i as intake. My H110 is exhausting air up and out with 140mm push fans. With my set-up, all the hot air from the GPU's is being pushed out the back mesh or sucked out through 140 rear. It never makes it up to the 140x2 in the roof which is why the full GPU load test doesn't alter my CPU temps. The top 120mm fan in front is partially obstructed by my H110 hoses and the rad and fans, but it is still pushing fresh air directly into the H110 fans, so I've almost got the same effect.

The key question is whether you need to run the H100i as a fresh air intake. Surely there are other 4790K owners with an Air 540 and a H100i/105 in the roof who can weigh in with their CPU temps and experience.

There is no doubt taking cool air from outside the system would lead to cooler CPU temperatures in test conditions, but reality and overall system health may be different. The warm air from the rad will be dumped into the case and I am sure the top exhaust will pull most of it out it out, but it may warm up the right side of your mobo on the way. The back exhaust fan will also pull some of it deeper into the case. My concern is you might not have the desirable amount of positive air flow into the case. You likely will set the rad fans to run in accordance with CPU temp. If your CPU temps are high, more air (warm) will be pushed in, but a lot less when under moderate loads. You also want that air evacuated out of the case as quickly as possible through the top which means you need to run the top fans at a decent speed. Running the H100i fans to increase airflow into the case will not have the desired effect. That leaves 1x120 providing most the air in and you may need to run it at a good clip. Then you have 1x140 in the rear and 2x120 in the roof (you likely will have to use 120's). This is probably always going to be a negative pressure system. Not necessarily a problem if you keep if off the floor and you don't live in the Outback. That said, in my arrangement I am amazed at how little dust I've accumulated. I went to do a three month cleaning over the weekend, and I couldn't find anything to do. Just a little dust on the front filter. My last system was unavoidably a negative pressure system and this is a nice change.

You will have to use 120mm fans in the roof if you want to the hoses on top. A front 25mm thick fan and the 27mm on the rad will put the combination within 1-2mm of 140mm mounted top fans. The 120mm mounting holes will gain you 25mm of space on the roof from the front. Even if you put the hoses on the bottom, this will be a very tight fit. I am a little worried about running the hoses around your GPU if in the bottom position. The stupid GPU's sag enough as it is these days. Below is the closest image I could find to illustrate the problem.

http://img.tapatalk.com/d/13/07/31/veva4ere.jpg

That's a 240mm rad with 120's in the roof. Add 25 mm toward the front to see where a 140mm fan will end.

The fact is you don't have to decide until you get your hands on the hardware. The H100i will fit in the roof or on the front. Your 120mm airflow fans can go on the front x3 on in the roof x2. A 140mm for the rear is included. Your parts list is interchangeable for both configurations. You may decide one way or the other is more desirable when holding the pieces in place. Worst case scenario is you wind up with an extra 120mm fan.

Cheers c-attack, there's some great points in there which have really got my thinking back on the right track. The picture was also a great one to help me visualise it a bit clearer. Ironically the worry about negative pressure was one of the reasons that I first got thinking about changing up the standard config for an Air 540 with top mounted H100i. I somewhat simplistically calculated that two 140mm intake fans would be hugely outperformed by one 140mm and two 120mm exhaust fans working together. I never even considered how significantly the 120mm fans would be impeded by having a large radiator sitting on top of them. So my solution to this "problem" shifted and changed until I had the theoretical set up of three 120mm intakes (Two impeded by a rad) going up against three completely unobstructed 140mm exhaust fans... Genius :-P Sure, that's why talking these things out in a knowledgeable forum is a good thing!

So to answer your question: No, it's now definitely not essential that I run the H100i as an intake. Between the realisation of the impact of the rad on airflow, and the physical impediments you pointed out, it now looks pretty clear that I ought to go with the config I had at the very start of my build plan, ie. Leaving the three 140mm fans in their factory positions and simply adding in the H100i as a top mounted exhaust. If the two rad mounted 120mm fans can't match the airflow of one of the unobstructed 140mm intakes, then I'm guaranteed positive pressure. At worst I can't imagine I'll have anything worse than neutral pressure inside.

My order for the extra airflow 120mm hadn't actually been processed yet, so I was able to cancel that without any cost. The only order I have in now is for a couple of upgraded static 120s for the rad, as I've noticed that the stock H100i fans get a pretty awful reputation from just about anyone that reviews or uses them.

I'll see how it all shapes up once I actually put the hardware together, and I'll be sure to return to give some feedback afterwards. You never know when someone else might have a similar question I guess! With that in mind, if c-attack or anyone else thinks of anything that can add to the topic, please do continue to share as well.

Thanks again,

Tipp Red