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Thread: PC Air Cooling Tips: Fan and Wire Placement

  1. #16
    Member polarnomad's Avatar
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    well, i'm a little worried about the increased noise of two more fans. that would bring the total number of fans up to 9, and i'm not too crazy about that.

  2. #17
    Senior Member Dracas's Avatar
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    Ho-lee-cr@p is this an old thread.

    I was rather shocked to see a reply notification in my email account

    Over a Year!

    Anyhow - Fans don't create noise in the fashion of 'compounding interest', the system will only be as loud as the loudest fan installed, and while the 'range' of the sound might be greater (from the various motors if you use different types of fan), then no, the sound won't be that much louder overall.

    I have *counts* 10 fans total in my case, and I can't even hear it when the ceiling fan or television is on, so don't worry about it, pop a few bucks for some new quiet fans.

    Alternatively, you can just leave them alone. Positive case pressure isn't necessarily the point of having fans installed. What IS important, is the amount of air and pattern of the air being streamed into the case. To keep it effective, its best to have the front fans blowing in, with all the rear fans exhausting, doesn't matter if there's empty fan ports or not (except, you might consider moving a fan to the front and letting the rear radiate). That could be totally a matter of opinion, but I've been running my current OC'd system like that for, well, almost a year.

    Cheers
    "Save us Booze, show us the way!"

  3. #18
    Member polarnomad's Avatar
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    Thanks Drakas. Yeah, I didn't think I would get any responses since the thread was so old, but since it was pertinent I thought I'd just give it a shot.

    I'll definitely try moving the second fan to the front. Then consider investing in some quieter fans. Thanks again for the helpful post.

    Fan placement seems to be a rather confused subject. So many people have so many differing opinions about what's best.

    Hey, a second question came to mind... A friend of mine was saying that fans are more efficient as "blowers" rather than exhausts. Any thoughts?

  4. #19
    Senior Member Dracas's Avatar
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    From independent research, the suggestion that blowers are better for moving air into a case is pretty much true. Most cases don't have or cannot achieve positive case pressure, so using a blower for exhausting hot air isn't nearly as efficient as, say, keeping a steady stream of cold air moving into the case from the front.

    The reason I say that (again) is because pressure isn't the point, RATE is the point, the higher the rate of air moving over a convecting surface, the quicker it can remove heat from that surface (which includes a mainboard, heatsinks, chips, etc..). By blowing cool air into the case, you're effectively increasing the rate of air flowing over the convecting components. Meanwhile, that airs got to go somewhere, so in most cases it will push itself out of the case back, or if you have fans installed back there, it will act as a bit of a 'guide' directing the stream from the front of the case, to the back exhaust, keeping ideal air movement at a peak across the central part of the mainboard.

    In terms of an entire cooling system though, front-in rear-out is the best setup for basic rectangular case like this, if it were a special case, then special cooling might be needed to get an ideal flow and rate. This is why I hate passice cooling solutions, and why they often fail to perform - the heat may be travelling up the pipe, but with little or no rate of heat removal from the heatsink itself of a given passive cooling solution, it has nowhere to go, and has to rely on natural laws of thermodynamics to do the work a fan would, which is slow.

    Okay, what now? Did that make sense?
    "Save us Booze, show us the way!"

  5. #20
    Member polarnomad's Avatar
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    Very clear thanks. So, basically I'll move the fan to the front, leave the rear slots vacant, and when I decide it's time to purchase more fans, by placing them in the rear they'll help guide the air out. Then later I can hunt down the most noise toxic fans currently in my case, replace them with silent ones and thus improve the overall noise factor.

    Cheers and Merry Christmas to ya!

  6. #21
    Junior Member bigboyslim's Avatar
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    I have a case that only has one hole in the rear to place a fan, and nothing else (besides power supply). Since I can only put one fan, should it be an exhaust fan? I found a fan that claims to have a 84 cfm output. Should I use that fan for my computer? Any help would be appreciated

  7. #22
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    Would think that closing them would be better than leaving open. And may not need to add two more fans and the ensuing noise.

    And definitely keep the computer out of the sauna!!

    "hullujua nuo suomalaiset!"

  8. #23
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    If you only have one fan, it should be input. Positive air pressure generally has two reasons: 1) Make sure that any openings only exhaust air so that dirt will not be introduced. 2) Make sure that you do not "starve" any exhaust fans, in particular the fan on the power supply, which is often a low power fan.

    The effect of hot air rising increases as there is more heat in the case, but for any given amount of heat there is a specific amount of this effect, in an appropriate environment this can be measured as cfm just like the fans in a case and this effect can be overwhelmed by significant fans in a case so that the philosophy of cold in at the bottom and hot out the top would be irrelevant. The pockets of hot air that are not removed is often the greater problem.

  9. #24
    Senior Member Happy Joe's Avatar
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    Geeze! a blast from the past!
    I have a case that only has one hole in the rear to place a fan, and nothing else (besides power supply). Since I can only put one fan, should it be an exhaust fan? I found a fan that claims to have a 84 cfm output. Should I use that fan for my computer?
    basicly... if it fits try it, if it doesn't fit mod it.
    Extra fans can be added in the front back or top, how the beast looks afterwards though is basicly a matter of the skill of the modder. (So if you are not familiar with metalworking techniques you might want to avoid modding, or at least aproach it slowly and carefully)

    An 87 cfm fan will almost certainly be noisy if it is an 80 mm. Try it blowing into the case and see if there is an improvement. Better yet try it both ways and go with the better solution. Many people try to ballance the inflow and outflow cfm.
    Blow holes (cut into the top of the case) with a fan blowing out are usually one of the best bang for the buck ventilation mods. A good second choice is to have an exit fan high in the rear of the case. People have relocated their power supplies then installed a fan in the old power supply location to get better exhaust.
    Others have replaced 2 of the drive bay inserts with a fan blowing in to supply cool air to the processor. Another option is to use the existing hole to blow air into the case then add another fan inside the case blowing into the powersupply to improve the exhaust.

    lots of people immediately replace the flat cables with round ones to improve the airflow inside of the case. A little thought and some creative bending can allow the flat cables to have superior performance if they can be run flat along a side. (some peole have rolled them to aproximate a round calble).

    I typically minimise the wiring clutter within the case by cutting the unused wires at the point where they attach to the buss within the powersupply and removing them completely (if you are not familiar with wiring and don't know enough to unplug the powersupply before taking it apart you should avoid this (one wrong snip and you would have to replace the supply (unless you can solder) (also there are potientially hazardous (deadly) voltages inside when it is plugged in)

    And remember wire ties are your friends...

    Just some random thoughts..
    Enjoy!

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