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General Fan Performance Guide 95

Posted by Hemos from the getting-it-working dept.
Lars Olsen writes: "As a complementary article to his comprehensive General Heat Transfer Guide , Dave Smith has written another great article for Amdmb.com called General Fan Performance Guide. This is an indepth guide to the performance of the fans we have in our PC's. Here's a quote: 'The specific purpose of this guide is to take the science associated with fans and translate it into a meaningful document that will allow the reader to understand how fans work and how they apply to computers. It provides a brief summary of DC power and drives. It finishes with an introduction to the concepts of sound generation and measurement.'"
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General Fan Performance Guide More

General Fan Performance Guide

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  • Heat Transfer Tip (Score:3, Interesting)

    by jeeryg_flashaccess ( 456261 ) on Tuesday October 30, 2001 @12:26AM (#2495988) Homepage Journal
    Change your thermal paste every now and then! Why do i say this? A K6 200 at work was blowing hot air...and freezing...The paste was hard as rock. I scraped it off and put new paste on. It blows cool air now, and runs better. BAM!

    • Re:Heat Transfer Tip (Score:3, Informative)

      by morcheeba ( 260908 )
      Actually, you want it to blow hot air! That's the heat from the chip... if it blows cold air, then the heat isn't making it to the heatsink and you've got a problem. [automotive parallel: if your heater doesn't blow hot air, then your cooling system isn't working; same situation]

      IIRC, AMD was recomending phase-change material instead of paste for just this reason. The paste works better... until it dries out. The phase-change material lasts longer. Just wondering... is it just me, or this the phase-change stuff seem like starburst candy? I removed my heatsinks and didn't want to reuse the p-c stuff, so I had to use paste. Could I have used a small slice of orange chew instead?

      Also, everyone else, when he says "freezing" he doesn't mean cold (like I originally thought), but locking up. Took me a few seconds to figure that out. BAM!
      • Thanks for clearing up my "freezing" statement. Didn't think about that one :) What I meant about it blowing hot air was...really hot air. I figured out it was running too hot when I burnt my finger on the heat sink. It's not blowing cold air now, but it's a heck of a lot cooler than before. BAM!
      • AMD was recomending phase-change material instead of paste
        Changing phase consumes a lot more energy than heating something that remains as the same phase. For example, assuming constant energy input, it doesn't take long to get the water in a kettle to 100 Celcius, but it takes a while to boil it all away (to change it's phase to steam). Plus, for all of that time the water is at 100 and the temperature doesn't climb again until it's all changed phase.
        Could I have used a small slice of orange chew instead?
        If it has high thermal conductivity you'll be OK until the ants get it. Maybe that's what he was using in "PI"?

  • Fan monitoring in Linux (Score:4, Informative)

    by CmdrTroll ( 412504 ) on Tuesday October 30, 2001 @12:29AM (#2495994) Homepage
    For anyone out there (myself included) who got the hankering to monitor their CPU fan speeds under Linux, try out wmalms [geocities.com], a handy dock applet that reads the I2C bus and reports fan activity. It could save your CPU.

    -CT

    • It all depends on which kind of CPU you have. PIII or P4, your machine with either lock up or run considerably slower (respectively) with complete thermal dissapation breakdown. If it is an Athlon, then yes, you'll want to watch your fan health like a hawk... I only say this because of this article [tomshardware.com] on Tom's Hardware. It is a little over a month old, but I was simply amazed when I first read it. Athlon owners are especially encouraged to read this, because it just might save your processor AND motherboard. Hope this helps someone out there.
      • It seems as if even good old Tom can be bought and sold [amdzone.com] these days. Damn shame.

        Looks like there is even a video [amdzone.com] of it!

        Why would Tom go and report something like that?

        • This argument [amdzone.com] is still going on. I wonder why companies resort to this type of tom-foolery. It makes me wonder about the authenticity of all the fan performance guides and papers.

          There has to be something more effective that we are overlooking in the processor cooling arena. Water-cooling is neat, but I try to keep my case dry, and the thought of adding a water pump running all the time to my water bill makes me cringe.
          I thought peltiers were cool for a while but now I wonder about them as well, with many people saying that they aren't as effective as reported.

          I guess the argument goes back to the old "ugly beige box" syndrome, and how its effected the PC industry. I would imagine that there is someone out there that could design a much more effective cooling system if they would drop all of the pre-thought notions that it has to be a box.

          Am I overlooking a previous slashdot story?
          • the thought of adding a water pump running all the time to my water bill makes me cringe
            This is a good point, the water bill for my water-cooled car is horrendous, I'd hate to have to start paying such a bill for my computer.

            I thought peltiers were cool

            HA, thats funny.

            now I wonder about them as well, with many people saying that they aren't as effective as reported.

            I've used them, and they can be extremely effective, but until that new kind we had a story about recently show up, they generate a heck of a lot of heat for the work they do.

            • Yeah, gotta look out for those water bills!

              Ok, ok, of course I meant my electricity bill.

              What about some sort of containment device that attaches directly to the outside of the case, allowing either cold air in or hot air out? Hell maybe both. Its a general idea now, but Im talking about a tube to channel air from a fan in the back of the case, to the cpu, and then from the cpu to the back of the case, creating a wind tunnel of sorts.

  • The most techno-geek of all fan articles is ... (Score:3, Interesting)

    by jkorty ( 86242 ) on Tuesday October 30, 2001 @12:32AM (#2496005) Homepage
    The best fan article I've ever seen I ran across entirely by accident a year or so ago:

    COOLING FAN NOISE - SLEEVE BEARING VS. BALL BEARING [comairrotron.com].

  • Just what Slashdot needs... (Score:3, Funny)

    by Black Art ( 3335 ) on Tuesday October 30, 2001 @12:41AM (#2496022)
    Another fan page.

    *rimshot*
  • I have to agree that this was an excelent article.

    But the gist of the article was essentialy what everybody knows... Move more air with less blades and less RPM and you have a better fan.

    I do not mean to down play all the valuable equations and (the very handy) conversion tables, but didn't this article say what we already knew just in an engineers terms?
    • Guess I'm not as geeky as I thought... Why is a slower fan (lower RPMs) a better fan? My Orbit runs at about 7200RPM and is about 5 degrees F cooler than the same computer without it.

      Can you explain?
      • Fan that can move comparable amount of hot air but with less RPMs means a quieter machine :)

        Personally my fans are the main source of noise in my home machines. I am in the process of looking for quiet case fans and will most definitely get a quieter CPU fan too.

        I am quite surprised at your CPU being 5F cooler though.....thought it would be far higher. Does your case have a lot of fans in it already, or do you have a low power unit like VIA's C3??

        Regards,

        Po
        • I have a stock fan on one box, and an Orbit on the second. The orbit is much taller, much higher RPM, moves much more air, and yes, runs much louder.

          I'd like to see a Tom's Hardware article on CPU fans, actually, as mine is quite loud...
          • Buck,

            Tom would probably recommend you run an Intel Pentium 4 complete with *no* fan at all. Voila! The sound of silence :)

            On a more serious and informative note, regulars of /. would be well recommended to have a look at Dans Data (http://www.dansdata.com/), as he loves heatsinks/fans/coolers to the point of obsession.

            Regards,

            Po
    • I didn't know a lot of that stuff, and I'll be damned if I still don't. Suffice it to say I won't be overclocking my cpu.
    • The generalization you made isn't always true, if you read the article. The more air not necessarily better, and the article shows that a balance is much more important than say having only 5 fans blowing air in or only 5 fans blowing out air. It's the flow that the author is trying to get across -- among other things.

  • iMacs have no fan, Mac+ also silent, and Apple II (Score:2, Interesting)

    by Anonymous Coward
    iMacs have no noisy fan, Mac+ also silent and fanless, and Apple II was fanless, and apple II GS and the NeXT had a eight foot set of cables to hide a cube 10 FEET from your ears.

    Fan noise is obnoxious. good designs use cold cpu chips like powerpcs.

    Apple exists in part because its machines run cool and sometimes run fanless and have many enthusiasts of utterly quiet workspaces.

    SILENCE IS GOLDEN.

    • Don't forget about the mac cube, too... lots of compute power & no fan, either!

  • Who needs a fan... (Score:3, Funny)

    by jpm242 ( 202316 ) on Tuesday October 30, 2001 @01:04AM (#2496059) Homepage
    when you live in Quebec?

    Just put the computer in a garbage bag and throw it in the snow. Cheaper than any cooling setup. Need extra long cables though, and you may need to relocate while the show plow passes.

    Another alternative is using a shop-vac, which can be switched in blower mode. You can put the device in the garage, and using a few dozen feet of plastic tubing, you can route that cool air right to your CPU. Lots of cubic feet of fresh air per minute. A bit noisy, but, listen to this folks, it doubles as a vacuum cleaner! How cool (no pun intended) is this?

    Think different!

    J.
    • If you live in upstate NY, and you are poor!!


      Can't afford plastic for the windows, (the things you look out of, not the OS =) and you can bet my thermostat for the house NEVER gets anywhere near 60.


      Then, keep your machines in your unheated attic, and you've got 6 months of sweet, sweet computing. Tho it is tough to type in your mittens.

    • I do this... I live in Salt Lake City (not nearly as good as Quebec for this sort of thing) but every year I get in about 3-4 months of excellent overclocking on my gaming box by sticking it on a small, protected ledge just outside the window where the temperature is usually at or below freezing. The machine runs 24/7 that way throughout most of the winter, and I can get an additional 70-100 MHz out of it with a CPU temperature that remains quite low. Last year I also was able to crank my (then new) GF2-Pro much higher as well.

      I'd never do it on any of my work machines, but it lets me crank the game visuals up during the snowy months on the game system.
  • I'm not sure it's actually funny, but it should earn me idiocy points.

    While reading the article I stuck my hand inside my case to get a feel for the air flow, and managed to nick the tip of my finger against the heat sink fan. Ouch. No apparent damage to my finger or the fan, but sure did make me jump.

    For those who are wondering why I had an open case, I've been replacing a partially failed hard drive (IBM Deskstar [slashdot.org] at that, lasted 14 months).
  • At work I've got a GeForce3... does anyone know of a good fan (read: the card won't melt away) that's quiet? The high pitched noise coming from the original fan is driving me nuts.
    • At work I've got a GeForce3... does anyone know of a good fan (read: the card won't melt away) that's quiet? The high pitched noise coming from the original fan is driving me nuts.

      not a fan recommendation, but i've found that a little bit of acoustic foam on the inside of a case does wonders to get rid of higher frequency fan noise. i put some on the inside of my case, and it's done wonders to keep the noise from my 7500 rpm cpu fan under control.

      it's a pretty easy install, too. just wipe the dust off the case metal, spray on some 3M spray adhesive, and put the foam there. reassemble the case and you're done.

      i got my foam at 2cooltek.com if you're interested in investigating further (store -> case supplies and coolers -> case mod supplies).

    • If you read the article, it describes the benefits of using 7 volts instead of 12 volts to run your fans. I have had my Duron and GeForce2 GTS both running on 7 volt fans for a long time -- the GeForce2 fan is now inaudible!

      Take a look at 7volts.com [7volts.com] for some more analysis.

  • Quiet cases? (Score:3, Interesting)

    by MisterPo ( 520698 ) on Tuesday October 30, 2001 @05:54AM (#2496317)
    Just a thought about quiet PCs. If the weight of a box is not too much of a problem, then lining the case with a car audio sound deadening may be an option.

    For example example Dynamat (http://www.dynamat.com/), has a range of sheets that are normally used to line car panels. These not only adsorb sound but heat also. So why not??

    That way you can have as many fans as you want in a system and barely hear them :)

    Regards,
    Po
    • I thought dynamat was for damping vibration, not absorbing sound???
      • Um, sound is vibration (you know, rattling the hammer and the stirrup causing them to stir different vibrations which tickle the "hairs" on the cochlea)...
        • Yes, I get the distinction. But there is a difference between stoping an object from vibrating and absorbing the sound already bouncing around in the air. I thought dynamat was for stopping your pannels in your car from vibrating due to a subwoofer or whatever. Accoustic foam like you would use in a studio has cones all over it for breaking up the sound waves.

          Years ago, when my dad worked at BBN, he said the accoustic engineers there had a room that would basicly null out all external sound. It had nothing to with padding or insulation, it was in the way the walls were textured. He said pretty much the only thing you could hear if you stood still was your own hear beating.

          I've never worked with dynamat, so it may indeed absorb sound as well. I was just curious, I didn't mean to sound like I was contradicting the parent.

    • try outgassing nitrogen or just getting drunk (Score:2, Funny)

      by Anonymous Coward
      The acustic properties of this must be considered.
      If you close the thing up completely then
      the heat won't escape as the sound deadening
      will most likely also prevent heat from escaping.
      Ideally one would have a system with air flow to a colder outside source and the whole thing
      closed up.
      One must consider what frequencies and by how much
      one wants to deaden the sound. Padding the inside
      of the case seems like a fire hazzard to me.
      I would pad the OUTSIDE of the case if that is
      what you want to do.

      Remember, the padding might touch power components
      and thus be exposed to very high temps and ignite.

      Nice for insurance money if that is what you want.
      I would rather have my house not burn down.

      It isn't just lower sound that you worry about
      but also safety and thermal control. Thermal control is why the fan is there in the first place.

      Remember, if the outside air is hot then the
      cooling effect of the fan will be incorrect.

      For extreame cooling with very little sound (no
      sound) use copper pipping and a full nitrogen tank. Make a coil or laberinth base with the copper pipe (a flat snake all bunched up)
      Have your tank out of the room. Have the pipe come through the room. It will be a platform which the computer is mounted over (but not on as
      that would be too cold.)

      Open the nitrogen valve. The nitrogen will flow through the pipe and create incredibly cold temperatures. Ice will form around the pipe (which is really pretty cool). This quite system is expensive and unconventional. Make sure the nitrogen vents outside. This system has been
      in use for years in labs where liquid nitrogen is 'free' in that one just needs to refill one's own tank. If you have to pay for the nitrogen then that's a bummer. But you gotta pay or the whole damn econmy grinds to a stinking halt.

      So now you know the quitest way to cool something. There will be sound at the tank and at the release at the end of the pipe, so put those outside the room.

      PS: just so you know that there are other uses for this, you can rap the copper pipe (1/4 or 1/2 inch in this case) around a keg and then outgas the nitrogen. That'll keep your brew chilly! Hey, and for you folks making music, you can put the CPU right next to the keg. . . (which will be frosted into a spirl of ice).

      We did this in our lab for our summer party.
      Gotta love that nitrogen tank.

      Drink up, boys. Less talk and more heavy drinking.

  • Fan Performance Poor (Score:1, Funny)

    by Anonymous Coward
    Usually, they're virgins, and they tend to be a little too... eager.

    <whisper from off-stage informs me that we're talking hardware>

    Nevermind.

  • a quite fan is important for music production (Score:1, Interesting)

    by Anonymous Coward
    A quite fan is a blessing!
    Especially if you are trying to make music!
    The solution of putting the CPU in a
    different room doesn't work that well in a
    home studio environment.

    Great article. It is good that
    everything is always about rivalries in
    industry.
  • But this story really blows
  • I'm sorry, wasn't "General Fan" one of the characters from "Crouching Tiger, Hidden Dragon"? I think his performance was just fine.

    (avoiding rotten tomatoes)
  • I read with interest the article on system cooling fans.

    I really think the type of cooling you need really depends on the architecture of the entire system case itself. For one thing, if you want lots of hot air being pulled out of the system case through the power supply, get something akin to the Enermax units, which sport two fans on the power supply itself.

    Also, those little expansion slot exhaust fans--despite what some people think about them, :-) are actually quite useful, exhausting air out of the lower part of the system case. Expansion slot fans work especially well installed close to today's high-end AGP graphics cards, since newer cards using nVidia's GeForce3 and ATI's Radeon chipsets generate considerable amounts of heat even with small cooling fans installed on the graphics card itself.

  • reliable fans? (Score:2, Interesting)

    by unger ( 42254 )
    What I want to know, is how long these cheap little fans are going to last! This is really the most important issue in my mind.

    I have no scientifically controlled empirical data set, but my random personal experience with many types of fans is that few of them perform as spec'd for very long.

    Lots of engineering seems to be going into heat sinks, but without reliable fans what good is the best heat sink?

    The latest fan I'm about to test is a Sunon GM1206PTBX-A "Green" 60mm. If this one develops problems I'm planning on trying a fan from Sanyo Denki. At this point though, after talking to many fan distributors, I starting to think reliable fans don't exist.

  • Where are the vertical cases? (Score:3, Insightful)

    by jandrese ( 485 ) <kensama@vt.edu> on Tuesday October 30, 2001 @04:05PM (#2499287) Homepage Journal
    One thing that has been bothering me for some time is the amount of energy spent fighting convection in a standard PC case. Just look how often your primary exaust is a power supply fan--where the intake is about 2/3 of the way up in the case. Any air above the intake fan (HOT air) has to be drawn back down into the exaust fan or stagnate. I suspect that in most cases that hot air just stagnates (right up where you CD burner, DVD and possibly even hard drives sit).
    Sorry for not including a small ascii art diagram that would have made the entire layout very obvious, but the lameness filter wouldn't even let a very dumbed down version of it through. Instead I'll try to spell it out here: (Ironically this is much lamer than just including a simple ASCII art diagram).

    The case has the power supply mounted in the normal location, however it is mounted such that the power cord connecter is on the top and the intake vents point downward. In front of the power supply (lining the top of the case) are the drive bays. The top of the case is an open mesh to allow air to escape easily. CD-ROM trays will open upwards (like the Apple Cube) and the floppies will drop in from the top. Each drive will have at least half an inch of space on either side of it to allow air to flow around it. The case will have three (possibly more or less) fans mounted in the bottom blowing upwards. The bottom of the case will be on raised legs that allow air to be pulled in from underneath the case. The motherboard will be mounted normally (since case manufacturers can't really do anything about it). Ideally though you would find some way to mount the PCI and AGP cards vertically.

    The rest of this post is an attempt to explain why I think this will work, and an attempt to avoid the lame lameness filter (why can't people who have good records, with say 35 or 40+ karma, get around the lameness filter?).
    Anyway, my primary intent with this case design is it reduce the turbulance in the case and to use the natural tendancy for heat to rise in my favor. The input fans at the bottom of the case should keep the entire case at a slightly positive pressure. One thing you must do with this case is sit it a couple of inches off of the ground espeically if the "ground" here is shag carpeting. The drives should not be as close together as they are in a standard PC case, and they should allow air to flow freely between them. In these days of 10k and 15k RPM drives cooling your HDs is perhaps one of the most often overlooked aspects if case design. The only big problem I have with this case is the PCI slots. PCI slots are generally too close together for my liking and they are almost invariably mounted horizontally, guarenteeing that any hot card will create a hot spot on the card above it. Unfortunatly there is little a case manufacturer can do about this so I'm leaving it as a caveat. Having the power supply mounted vertically will mean that the power cord will attach to the top of your computer. I recommend either a specialy modified power supply or mounting the power supply horizontally (with the intake repositioned to the bottom of the power supply) and lengthing the case somewhat or simply leaving the power cords on the top of the case. A crafty case manufacturer might even create a little box for the ends of the power cords on the top of the case that will conceal them from general view. If you need more 3 1/2 bays, you can run them down the front of the case (in front of the motherboard) vertically. The final caveat with this configuration is that your users must remember to never stick objects on the top of this case (especially things that can spill, like coffee cups). I recommend making the top rounded or triangular or some other shape unsuited for sitting things on (but remember to leave access for things like CD-ROMs and floppy drives!).

    A similar construction (albiet with more specialized hardware) to this was already used for that Apple Cube (and look how good the cooling was on that, no fan needed!) but it seems like PC manufacturuers still havn't got it. Look at practially any professional server and you'll see similar concepts in play (I'm definatly not claiming I invented any of this) almost exclusivly. Nothing here is new in the slightest and yet nearly every PC case manufacturer insists on the same general layout and same general poor quality construction. Sometimes it feels like the only thing cases are manufactured for is low cost, and all other considerations are secondary. It is this attitude of cutting every corner possible that leads to the air circulation nightmare we have in almost all modern cases. I also believe that high heat lowers the life of PC components, be it through shrinking and expanding or just plain mild constant overheating. This goes double for devices like hard drives which have actual mechanical components and thin layers of oil to worry about.
  • Oh my! I can't hear the fan in my computer! Is it broken? Will it go up in flames soon like that Athlon at Tom's Hardware? Or maybe.. wait!.. Now, look at that lovely Apple on the front! :-)

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