Air/Water Hybrid Setup - Help needed with airflow

[businessms]

Hello all,

I have a question regarding the optimal airflow setup of my build. Before I'll give you the details about my setup, let me start by saying this started out as a pure air-cooling setup. My CPU cooler to be was the Cryorig R1 Universal, but to my dismay the behemoth blocked my first PCI-E slot. Since this unfortunate discovery I've switched to the following hybrid setup:

* Mainboard: MSI Z170A XPower Gaming Titanium
* Case: Phantek Enthoo Luxe
* CPU Cooler: Corsair Hydro Series H110 Extreme Performance - finally, some space left for the GPU
* GPU: Palit Geforce GTX 1080 Gamerock Premium x2 (SLI)
* Case Coolers: a variety of the following:
* Phantek PH-F140SP (140mm, bundled with the case)
* Corsair AF-140 (140mm)
* Corsair PH-F200SP (200mm, bundled with the case)

Some additional notes/observations that might be of interest:

* The two GPUs are *huge*, in fact so bulky that they basically block all PCI-E slots of the mainboard. So not much airflow there. Their design is intelligent enough though, as most of the hot air seems to get exhausted through the mesh on the card's rear.
* The case is well-equipped with dust filters, so high positive pressure isn't a requirement for me. Besides, I tend to keep the environment of the build pretty clean anyways.
* The case comes with a PSU cover that might help to shield the PSU from GPU heat. The case is a full tower, quite some space between the lower GPU and the PSU, so I'm not sure how much of an issue this really is. An additional consideration: installing the PSU cover makes the bottom fan pretty much useless, as it is covered by the PSU shield.
* The optical bay and the upper HDD cage have been removed. This leaves just the bottom HDD cage, two (out of three possible) drives are installed. The lower front fan is thus more or less obstructed by the drivers.
* I absolutely, positively do not care about "the looks": this system is going to get overclocked hard, I favor performance over aesthetics - period

My original build was planned as follows:

Front: 2x Corsair AF-140 Intake
Bottom: 1x Corsair AF-140 Intake
Rear: 1x Corsair AF-140 Exhaust
Top: 1x Corsair PH-F200SP Exhaust

Plans somewhat changed as mentioned. It feels like I've read almost every article and forum entry on airflow, positve/negative pressure, push/pull - still: I'm not the wiser, as most articles seem to contradict each other. Also, many people seem to get the terms mixed up, so just to be clear, this is how I understand and use them:

* Positive Pressure: overall intake airflow exceeds exhaust. Seems to keep the dust out, but hot air will stay in the case longer (due to lower exhaust rate).
* Negative Pressure: overall exhaust airflow exceeds intake. Hot air gets expelled fast, but intake rate of new cool air is slower. Also, dust might get into the case more easily.
* Push/Pull: people seem to (mis)use this terms for all kinds of setups, but in my opinion they really only make sense in conjunction with water cooling/radiators. In a push configuration the fan sits "before" the radiator, pushing air through the radiator. In a pull configuration, the fan sits "behind" the radiator, pulling air through the radiator. Both push and pull configurations can be either intake or exhaust.

Phew - please, *please*: correct me if the above definitions are wrong, I'd really like to get this terms sorted out once and for all. This is my first hybrid/water-cooling build, so the top radiator is where I'm a bit stumped. On their website, Corsair recommends installing the radiator on top (fine), but ... as intake. How is this a good idea? Blowing hot air from the radiator down into a case that only has one exhaust fan anyways? Additionally, and thats about all I remember from high school physics: hot air has this tendency to rise, does it not? So, in my case and in conjunction with the poor lonely exhaus fan: wouldn't that mess up the airflow completely?
Now, finally, to my question: given the above setup and considerations, how can I achieve optimal airflow? I have though of something like this:

Is this a good idea? Bad? If so, why? Is this underpowered for the intended use (overclocking), or even overkill? Should I leave the PSU cover on and sacrifice the bottom intake? Please share your experience, comments from owners of the same case/cooling system are of course of special interest to me. My final question would be: radiator - push, pull, or even both (if space allows it)? I know I know, the age-old dilemma ;-)

Thanks for reading this and any help I might get!

 

[Eximo]

They recommend doing that to get the best possible temperature difference between the radiator and the ambient air.

I think it is stupid, because it turns your radiator into a giant dust magnet. Better to have filtered intakes and the radiator as exhaust. And yes, that would be the more natural flow.

Your definitions of push/pull are correct, however they apply to all radiator types, that is what a heatsink is. You can have the fan pushing through the heatsink (the most common configuration), or do push and pull through a heatsink. GPUs and CPUs are down draft coolers, and so can't really be push/pull of course.

Positive pressure is desired for dust control, yes. But still requires filtered intakes.

Negative pressure is how many older style computers were built. Unfiltered intakes, or no intakes (simply vents) and top/rear exhaust only. That is why so many of that style case end up with clogged front panels.

 

[businessms]

Thanks for your reply Eximo! The clarification regarding radiators vs heatsinks was especially helpful. Also, it's good to know that I seem to get the basics. Would you use the bottom intake,or use the PSU Cover as a heat shield? If possible,I'd really like to use the push and pull configuration with the H110,as my fans seem to be lacking a bit in the static pressure department. I'm guessing such a configuration would leave me on the negative pressure side of things.Again,I think this would not be much of an issue in my environment. Any other tips regarding my proposed Setup? Thanks again for taking the time to help me out guys.

 

[Eximo]

I do use the bottom intake on my PC, but it also is filtered. If you have a full length PSU cover and no components down there to cool, sectioning it off is probably best.

I would think the H110 would be okay with a single set of fans in either configuration, but if you have the room, why not. Possibly, depends on the actual airflow going in and out. You can always try to shift it the other way by increasing fan speed.

At a certain point it doesn't really matter. As long as the components stay cool.