Airflow in the case

Following a rebuild, I am now in a quest to lower my CPU temperatures as low as possible. I tried to attach a JPEG to show the current air flow but that attempt has apparently failed. So, I'll try to describe what is going on in the case currently.

PSU – located at the top back of the case; draws air in through its bottom and exhausts out the back of the case

CPU – air is drawn in through a vent in the side of the case, ported via a plastic cone to within a couple inches of the fan that drives air into the CPU cooler fins. I have added a small fan in the plastic cone to aid the bringing of fresh air into the cooler fan as expeditiously as possible

Added large fan on the back of the case – I added a large (5 inch?) fan that is currently exhausting air from the entire case – that fan is immediately below the PSU and on the back of the case.

My concern is that the large fan at the back of the case may be preventing the PSU above it from drawing enough air in from the inside of the case to adequately cool the PSU (remember that it's exhaust runs back out the case).

The question is, would I be better to use that large fan on the back of the case as an intake port to bring cool air into the entire case and allow the heated air exhaust to occur up to the PSU and through the vent panel at the bottom of the side of the case?


7 answers Last reply Best Answer
More about airflow case
  1. Is that all your fans? If you blow air in from the back, won't that work against the two you have blowing in at the CPU? I would let the back one be the main exhaust, and let the PSU take care of itself.
  2. What case do you have?
    What graphics card?

    The job of a psu fan is to cool the psu, nothing else. Do not count on it to help with case cooling. The psu fan will spin up if necessary. A gold rated psu may not normally spin it's fan at all.

    I do not much like side vents, I think they disrupt natural front to back, low to high airflow. If it is the only possible intake, then ok.

    I would leave the rear fan as an exhaust.

    I am not so certain of your duct either. The motherboard requires some cooling airflow too.

    To get low cpu temperatures, use a decent aftermarket cooler. Try to have two 120mm intake fans, and an equivalent amount of exhaust area.

    Lastly, remember that a cpu can operate at high temperatures. If it gets dangerously hot, it will downclock to protect itself from damage.
  3. My theory on Case Air Flow has always been intake in the front. and exhaust in the back. if you have top ports set them as exhaust as well. but that depends on your case design. some cases are designed to hold air. so don't take the side of your case off unless you get a better temp rating with it off ( Which can make your computer dusty depending) But do try to have a balance of intake and exhaust. I have 1 200 mm front fan as well as a 80 mm in the drive bays blowing air in to the CPU cooler. the two top and rear 120mm is exhaust. also depending on what your fan speeds are can be throwing out air faster then you can tanke some in. but i could be wrong
  4. Best answer
    I like even-ish pressure in the case. I suggest you put a fan drawing in from the bottom front (hdd bay), one exhausting in the back and since you have psu that blows air out as well (though don't think they blow that much) it is alright to keep the side fan over the cpu.
    What you currently have will cripple the airflow to your gpu. Bottom front intake is a must.
  5. Oh and put a dust filter on your intakes. Bad things happen if you dont!
  6. Thank you to everybody who offered suggestions concerning the airflow problems in my case.

    I ran some experiments with different fan configurations and came to the conclusion that the large fan at the back of the case should definitely be exhaust and that the fan inside the cooling cone driving outside air toward the CPU cooler would remain. With that setup, I mostly run CPU temperatures of 49-60 C. I would like it to be cooler (especially before we get back to warm weather) but I'm reasonably sure that I will have to get a heftier cooler for the CPU than I now possess.

  7. Best answer selected by maestrogn.
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