Thermal grease

By Malditohon
Mar 30, 2008
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  1. kimsland

    kimsland Ex-TechSpotter Posts: 18,353

    I have another dumb question! (indirectly related to the heading)

    I have a fan at the front of my case sucking air in (actually straight on to the HDD)
    I have a CPU Fan suckig air in (ofcourse)
    I have a rear fan blowing air out (another ofcourse - getting rid of CPU heat)

    This setup creates an airflow, from front of case -> out to rear of case

    Is this right ?

    Someone told me (today ironically) that all case fans should blow air out
    But if I did this, it would stop the air flow (that may be non-existant anyway I suppose?)

    So, regarding CPU heat removing. Should all case fans (even if I get more) blow air out ?

    I hope this is not too off topic
  2. Whiffen

    Whiffen Newcomer, in training Posts: 323

    I would think blowing on the parts would make it cooler because fans like that don't have much suck. Most of that airflow doesn't even come from behind the fan so puting it in backwards thinking it will suck in the heat and blow it away might not work so well. If you see a logo sticker on the fan just leave it upside up ;d
  3. kimsland

    kimsland Ex-TechSpotter Posts: 18,353

    Thank-you for the reply

    But the back case fan does draw heat out (mounted near the heatsink)
    So therefore at least I believe that is ok (and not exactly what you said)
    I have confirmed that the CPU is cooler for it too.

    But the front fan (yes not much suck) So then maybe mine is ok (as this one is exactly what you said) Seeming it is blowing on the HDD anyway.
    And if I turned it around, I don't believe it will really get rid of much heat (ie front of case)

    I just wanted an official response from this, from any builders (Although I build too, I do not normally put front of case fans in) I believe there may still be some confusion here.
  4. Malditohon

    Malditohon Newcomer, in training Topic Starter Posts: 40

    a terrific question and what you say is right! there should be enough intake of air from one part of the chassis and greater amount of air flowing out would help.

    just like my chassis, there is an intake in front and air flowing out in the right side and also at the back and the power supply but typically it should be cleaned ones in a while to prevent dust from building in your board and other components.
  5. patrickh44231

    patrickh44231 Newcomer, in training

    this is the most recent topics i've been fallowing on thermal compounds.

    http://www.circuitremix.com/index.php?q=node/124&page=0,0

    and if your really into it look into thermal pads.

    http://www.coollaboratory.com/en/

    * http://www.burnoutpc.com/modules/smartsection/item.php?itemid=245 *

    i personally haven't used the pads yet(ordered them yesterday)

    and if your nitpickey enough to learn and take the time to really make the stock heat spreader & heatsink shiney and absolutly mirrored with a still perfectly flat surface it's worth it you'll drop a lil degreese with a nice buffing and sanding job

    http://www.watercoolingshop.com/cat...id=78&osCsid=a2e2539b11bf9f5eee7d77bdc396c642
  6. CMH

    CMH TechSpot Chancellor Posts: 2,572   +9

    Whoever told you that probably meant it as an april fool's joke.

    Airflow in the case doesn't really have to mean that you always have wind in your computer. It really just means that you're getting cool air in, and hot air out.

    So if you're saying that the back fan is blowing hot air out, its good.

    Blowing cold air continuously on a component may sound like a good idea, but you'll end up making other components heat up, since air around them would be static.

    I believe the ultimate case/fan setup would be a tunnel shaped case, with a fan on each end on a push-pull setup. Since our cases aren't cylindrical, the closest we can get to that would be having an intake fan in front, and an exhaust fan at the back. The fact that the exhaust fan would be positioned higher up, and closer to the CPU, helps.

    What you absolutely want to avoid is an airflow loop: air coming in somewhere, and going out again without actually cooling anything.
  7. kimsland

    kimsland Ex-TechSpotter Posts: 18,353

    Thanks CMH.
    As I don't know if the front fan is causing an airflow loop or if it is causing issues on static (no air flow) parts. How can anyone test this.

    I believe the information here is useful trying to cool their CPU (and M/b) starting from the correct Heatsink then Thermal paste the Fans (air flow) (and proper mounting of all 3).

    So again, do I leave the front (cheapo colored lights) fan there in the front sucking air in ?
    What do others do here. Does anyone put front fans in ?
    I should really get a box that has a fan vent in the top of the case (ideally) As heat goes up.

    Should I inform the guy that not all case fans should be mounted to blow air out.

    I forgot to mention I have 5 fans actually (The powersupply - new also gets rid of hot air via 2 fans one underneath and one out the back.)

    It's fan city here!
  8. CMH

    CMH TechSpot Chancellor Posts: 2,572   +9

    Here's my current setup:

    Front 120mm intake
    Back 120mm exhaust
    Top 80mm exhaust.
    80mm hole on top of CPU.

    I have actually tested having the top 80mm as an intake, and I had a 1C change in CPU temps, which I thought was negligible enough. As it was a year ago, I can't remember if it was a 1C increase, or decrease, but like I said, it was negligible, so I ignored it, and set it as exhaust.

    I've had problems with overheating HDDs before, so I didn't even consider having the front fan as exhaust. It doesn't seem to make any sense anyway having it as an exhaust fan. Feel free to try swapping it around, and record some CPU/GPU temps.

    Most of you would quickly note the 80mm hole on top of the CPU. Its not exactly on the CPU itself, but somewhere smack in the middle of the side panel. The real reason why its a hole, and not filled with a fan is because I have a Thermaltake Ultra-120, and this beast comes all the way up to the side panel, leaving absolutely no space (okay, maybe a few mm) for a fan, unless I want to mount it protruding from the case.

    Besides, I thought since it comes all the way up to there anyway, any cold air would end up going past the heatsink, which is a good thing. (right now, there's a fan guard blu-tacked onto the hole :D)


    As far as a box with a fan vent, like I mentioned, it didn't make any difference blowing in or out. I doubt it would make much difference if the fan wasn't there at all.

    However, if you have a particularly short case, then an exhaust fan might be a good idea.

    BTW, have you even decided if your temps are worth all this trouble? o_O We're talking about very minimal changes in temps here, I'd say a 5C decrease in temps would be the max you'd see, with 1-2C being more the norm.

    A good thing you might want to do which may help with airflow is to tidy up your cables. It might take a long time to do, but once done, poking inside your computer would be a much more pleasant chore, without having to shove all the wires out of the way to access something. Here's a photo of the insides of my case as it currently is, with my few hours of cable management. What you can't see in this photo is the management at the back of my case as well, which would serve absolutely no functional value, but given my case has a window on both side panels, and the top panel, I had to spend a real long time making sure the cables couldn't be seen at all from these panels.
  9. NFSFAN

    NFSFAN Newcomer, in training Posts: 340

    I would say go with either Arctic Cooling MX-2 or Arctic Silver 5. Those are the best thermal grease solutions on the market, besides the Coolab's Liquid Metal Pro.
  10. CMH

    CMH TechSpot Chancellor Posts: 2,572   +9

    Arctic Silver 5 is the only thing I'd recommend for now.

    The Coolab's Liquid Metal Pro is:
    a) too hard to obtain.
    b) pretty dangerous to heatsinks.

    b is there because that thing will dissolve any aluminum, which means you absolutely can't use it with aluminum heatsinks.

    Even if yours isn't an aluminus heatsink, you'd have to be really careful with it, as any contact with aluminum would be disastrous to any other aluminum product.

    In terms of temps, I think they're pretty similar to AS5.


    Someone did a comparison between a few different thermal greases, AND toothpaste, AND water.

    It turns out that water is the BEST thing to use, but you'll have to reapply it every few minutes :D:D:D
  11. wsnett

    wsnett Newcomer, in training

    can use any type or any brand thermal grease

    you can yiou any type or brand of thermal grease, only u must be carefull about heatsink and cpu fan
     
  12. captaincranky

    captaincranky TechSpot Addict Posts: 10,400   +832

    OK, The front fan draws air into the case, the back fan exhausts it. (Blows out).
    This is the same thing as cross ventilating your house.

    The rear fans are generally high in the case, right below the PSU which is always blowing OUT. If the fan under the PSU sucked air into the case, the PSU would pick it up right away and most of it would never get into the case. the rising column of hot air from the CPU would further cause the incoming air to rise into the PSU area.

    If the front fan were used as an exhaust, it would need to suck hot air down from the top of the case through the optical drives, since the front fans are generally low in the case.

    So, with the front fans drawing cold air into the case, this assists the natural flow of heat upward from the CPU, toward the PSU and out the rear fan.

    Any other arrangement for want of a better technical term, is just plain stupid.

    Did I fall for an April Fools Day prank?
  13. CMH

    CMH TechSpot Chancellor Posts: 2,572   +9

    Yes, any type or brand of thermal grease is good. Some are better than others of course, but the difference isn't much (5-6C? I'd be very surprised if the difference between a standard paste, and the best paste go above 10C)

    Correct application of thermal paste can make a bigger difference. Correct application is having the minimal paste, while covering the whole contact surface. May different suggestions are around for this, I personally just put a small amount (bb sized blob) on the CPU, and press the heatsink on. Other people suggest spreading it first, but whatever it is, the idea is not to spread it like a fat kid spreading peanut butter on his toast.
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