poulin@POLAR.BOWDOIN.EDU (Jeff Poulin) (12/13/90)
Here's a dumb little question that I'm not sure of the answer. Which direction should the fan be blowing: into the power supply or out of it? My computer came configured with the fan blowing in (presumably to keep the stuff in the power supply cool), but I noticed the cards become quite warm and one of the hard drives starts sounding like a car going 40mph in first gear if I leave the computer on for more than 12 hours. Otherwise it seems to be fine and the hard drive is fairly quiet. Any takers? -- Jeff Poulin poulin@polar.bowdoin.edu jpoulin@bowdoin.bitnet
zaft@nswses.navy.mil (Gordon C Zaft) (12/14/90)
In article <9012130133.AA24147@polar.bowdoin.edu> poulin@POLAR.BOWDOIN.EDU (Jeff Poulin) writes: >Here's a dumb little question that I'm not sure of the answer. Which >direction should the fan be blowing: into the power supply or out of it? >My computer came configured with the fan blowing in (presumably to keep >the stuff in the power supply cool), but I noticed the cards become quite >warm and one of the hard drives starts sounding like a car going 40mph in >first gear if I leave the computer on for more than 12 hours. Otherwise Fans on power supplies should never blow into the cabinet, always OUT. The idea is to draw cool air into the cabinet, across the cards, through the power supply and out. -- + Gordon Zaft | zaft@suned1.nswses.navy.mil + + NSWSES, Code 4Y33 | suned1!zaft@elroy.jpl.nasa.gov + + Port Hueneme, CA 93043-5007 | Phone: (805) 982-0684 FAX: 982-8768 + **** Gloria in excelsis Deo, et in terra Pax hominibus bonae voluntatis. *****
floyd@ims.alaska.edu (Floyd Davidson) (12/15/90)
In article <6606@suned1.Nswses.Navy.MIL> zaft@nswses.navy.mil (Gordon C Zaft) writes: >In article <9012130133.AA24147@polar.bowdoin.edu> poulin@POLAR.BOWDOIN.EDU (Jeff Poulin) writes: >>Here's a dumb little question that I'm not sure of the answer. Which >>direction should the fan be blowing: into the power supply or out of it? >>My computer came configured with the fan blowing in (presumably to keep >>the stuff in the power supply cool), but I noticed the cards become quite >>warm and one of the hard drives starts sounding like a car going 40mph in >>first gear if I leave the computer on for more than 12 hours. Otherwise > > Fans on power supplies should never blow into the cabinet, always >OUT. The idea is to draw cool air into the cabinet, across the cards, >through the power supply and out. > Fans should blow into the cabinet. If the power supply runs hot (not all do, but...) then air flow should be controlled such that the heat goes straight out, not into the rest of the cabinet. There is one simple reason for this. The only effective way to put an air filter in front of the fan is if it blows in. the filter can be directly in front of the fan then. You don't have a filter? Get one. Check this out. Take a look at good quality test equipment, say HP or Weco. 90% of it has the fan blowing in and has a filter. The other 10% is poorly engineered. Floyd -- Floyd L. Davidson floyd@hayes.ims.alaska.edu Salcha, AK 99714 paycheck connection to Alascom, Inc. When I speak for them, one of us will be *out* of business in a hurry.
bill@bilver.uucp (Bill Vermillion) (12/17/90)
In article <6606@suned1.Nswses.Navy.MIL> zaft@nswses.navy.mil (Gordon C Zaft) writes: >In article <9012130133.AA24147@polar.bowdoin.edu> poulin@POLAR.BOWDOIN.EDU (Jeff Poulin) writes: >>Here's a dumb little question that I'm not sure of the answer. Which >>direction should the fan be blowing: into the power supply or out of it? >>My computer came configured with the fan blowing in (presumably to keep >>the stuff in the power supply cool), but I noticed the cards become quite >>warm and one of the hard drives starts sounding like a car going 40mph in >>first gear if I leave the computer on for more than 12 hours. Otherwise > > Fans on power supplies should never blow into the cabinet, always >OUT. The idea is to draw cool air into the cabinet, across the cards, >through the power supply and out. Just because IBM screwed up the original design there is no reason the world has to follow. Fans should always blow IN to a system. And ideally they should have a replaceable filter. You have to design the cabinet properly, and your high draw chips should be the near the exit - take a good look at an S-100 box that is properly designed. The problem with blowing out is that the air comes in at ALL entrances to the system. Venturi effects create higher velocities nearer smaller openings and you such dirt into such thinks as chip sockets, and worst of all THROUGH floppy drives. That's a killer. Of the compatibles/clones Tandy had one run of their 3000 series that had a a power supply enclosed in a wide slot cage. The cooling fan drew in at the front of the machine through a washable filter. The air then came directly across the memory chips, and out through the power supply. They dropped that later - but it was one of the good things they did. You will see this approach in many of the newer '486 boxes - and I saw one that did the above, but used a dual stage fan depending on internal temperatures. Designers are finally starting to design things, not just copy a poorly designed piece of equipment. Pressurizing any component is the only real way to prevent hot spots, along with proper layout. -- Bill Vermillion - UUCP: uunet!tarpit!bilver!bill : bill@bilver.UUCP
bill@bilver.uucp (Bill Vermillion) (12/17/90)
In article <6606@suned1.Nswses.Navy.MIL> zaft@nswses.navy.mil (Gordon C Zaft) writes: >In article <9012130133.AA24147@polar.bowdoin.edu> poulin@POLAR.BOWDOIN.EDU (Jeff Poulin) writes: >>Here's a dumb little question that I'm not sure of the answer. Which >>direction should the fan be blowing: into the power supply or out of it? > Fans on power supplies should never blow into the cabinet, always >OUT. The idea is to draw cool air into the cabinet, across the cards, >through the power supply and out. A quick addendum in addition to my previous post. Everyone keeps thinking of the fan as part of the power supply. In a "assemble" the component type industry that at least makes sure the power supply doesn't burn up, but the fan really should not be part of the power suppy, it should be part of the cabinet, and the cabinet should be designed to direct the air flow appropriately. -- Bill Vermillion - UUCP: uunet!tarpit!bilver!bill : bill@bilver.UUCP
jonu@FtCollins.NCR.com (Jon Udell) (12/18/90)
> Check this out. Take a look at good quality test equipment, > say HP or Weco. 90% of it has the fan blowing in and has a > filter. The other 10% is poorly engineered. Thus 10% of good quality test equipment is poorly engineered? Sorry, I couldn't resist. -- ------------------------------------------------------------------------------- Jon Udell NCR Microelectronics Products Division Jon.Udell@FtCollins.NCR.COM 2057 Vermont uunet!ncrlnk!ncr-mpd!ncr-fc!jonu Fort Collins, CO 80525 (303) 223-5100 X431 -------------------------------------------------------------------------------