WTB Negative Pressure Airflow In CM HAF 912 w/ Hyper 212 EVO + Asus Radeon R9 270

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Frostfiresale

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Mar 20, 2014
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I am looking for advice on the airflow system in my first build before I go ahead with it's initial boot. My goal is to achieve negative airflow pressure with this build.

My case, the HAF 912 (not Advanced, btw), allows for:
Front: 2x120mm or 1x200mm
Side: 1x120 or 1x140mm
Top: 2x120mm or 1x200mm
Rear: 1x120mm

Current build:
Mobo: Asus Maximus VI Hero (5 fan headers, but I can use a splitter for more)
CPU: Intel i5 Core 4670k (w/ Arctic 5 Silver paste, full spread method)
CPU Cooler: Cooler Master Hyper 212 Evo (vertical placement w/ push, not push-pull)
GPU: Asus Radeon R9 270
PSU: Corsair CX750M
Memory: Western Digital Caviar Black 1TB
RAM: G.Skill Ripjaws X (2x4GB)
Case Fans: So far, just a single Cooler Master Megaflow 200mm and the two 120mm stock fans which the HAF 912 came with (I am still shopping for whatever fans I will need to achieve negative pressure and I have no issue with discarding what I currently have).

It currently looks like:

118lwk3.jpg


My CPU cooler is the Hyper 212 Evo and it is positioned vertically, with it's single fan pushing air thru the Evo's structure and towards the rear exhaust of the PC case. (I am also wondering if and how, all things considered, this will add to or take away from my goal of a negative pressure airflow system because I've read that you cannot go off of CFM numbers alone).

My GPU, the Asus Radeon R9 270, is just below the CPU Cooler and faces what I would call downwards (the bottom of the chipboard is facing upwards).
The two little fans on this GPU are facing downwards but, or at least I would assume, they blow air up onto the GPU. And that does what? I don't know. Does it just hit the chipboard and flow outward in all directions? I am concerned that the heat from the GPU is just stuck in an airflow dead zone in the lower rear of my case.
Or, since heat is supposed to rise, will it just run off the sides of the chipboard and rise up into the airflow current coming from the front case fan (or fans) and/or the push of the CPU cooler? If this is true, then I assume some of this heat would go through the CPU cooler and anything that escapes will be pulled by the fan (or fans) in the top of the case. I do not know.

And, finally, would putting a 1x120mm (or 140mm) in the side panel help or hurt the situation? (I assume a side panel fan should be intake, but I am open to any theories on a side panel exhaust if it helps in this particular situation).

Or, is the situation bad all around and I should just shop for another case?

P.S. I do intend to better my cable management, but I'm not getting into any further work until I'm ready to install/re-work fans.
 
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DarkSable

DarkSable

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Sep 27, 2012
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It's generally accepted now that you want a moderate amount of POSITIVE pressure, because negative pressure draws in air and dust from all the little cracks in the case.

You generally want to think about the direction that air is going to be flowing - so you want the bottom and front fans to be intake, and the top and rear fans to be exhaust.

You are entirely correct as to what the heat from the GPU is doing; this is why the fancy open coolers you see on manufacturer's graphics cards aren't nearly as good as they think, because they recirculate all the hot air throughout the case. You could put a side fan there to cause airflow to go in and up if you wanted.



The situation isn't bad at all, and I think you're freaking out over it WAY too much and not paying attention to when your research is dated. You want SLIGHT positive pressure, you want to avoid negative pressure at all costs, and you want to be using the biggest fans your case will accept. (Bigger fans move more air with less noise.)



I would personally do this:

1) move your CPU cooler to be blowing air upwards.

2) Change the front fans for a single 200mm fan - it'll make a big difference to noise.

3) Put a 140mm fan intake on the side panel, which will help cool your GPU and achieve decent positive pressure, keeping your system cleaner and the airflow circulating.
 
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Frostfiresale

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Mar 20, 2014
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I read that a positive pressure system causes long-term drawbacks (stagnant air shortening the life of your components, if I recall correctly). I read that it does help with dust, but I'll have a cleaning kit for that.
Rule #2 @ http://www.tomshardware.com/faq/id-1858957/airflow-101-setting-fans-keeping-computer-cool.html

I know that some would rather have less cleaning to do and not concern themselves with the long-term (as they probably upgrade every few years). I, on the other hand, do not plan on upgrading for a decade if I can manage it : )

Thank you for your insight all around, tho. Especially regarding the GPU.
 
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DarkSable

DarkSable

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Sep 27, 2012
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Mmm, I haven't seen that view in a very long time, actually.

That's a very simplified view of airflow, and only applies when looking at generalizations. Like I said, what you want is SLIGHT positive pressure; enough that dust isn't an issue but not so much that you get those kinds of issues that arise only in extreme cases.

If it helps, don't think about it in terms of positive or negative pressure - you don't want either one, period. The ideal cooling for a computer is a direct airflow current with completely even pressure... but you're never going to achieve that ideal, and it's better to err on the side of positive pressure.



Also, like I said... you're freaking out way, WAY too much over this. Unless you're having a serious problem with your temperatures, this is not a big deal.


EDIT: Oh, and in no way is stagnant air going to shorten the life of your components, come on... the worst it would do is cause you to have higher temperatures. If your temperatures get to the point where they're above what the chips can handle, then you have issues, but stagnant air by itself isn't going to harm components.
 
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Frostfiresale

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Now that you mention it, I'm not sure, at all, that I read that or just assumed it would shorten the lifespan. Thanks again. I might look into it further (have to wait until my next paycheck, anyhow), or not (I dunno, heh), while I see if anyone else has anything to add.

 
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