> > IIRC, in one of these threads it was asserted that the most significant > cause of noise is the _shape_ of the metal protector for the main case fan > on the backplane. Perhaps snipping this out and/or replacing it with a > welded wire protector would offer some relief ;-) > > Alternatively, reducing the speed of the fan [using a resistor or > potentiometer in-line; tapping from the +5 and +12 feeds to yield a 7 volt > potential] [1], and/or using a quieter fan [with ball bearing instead of > sleeve bearing; with better vane design] [2] might also help.
Alan, I went through various steps into determining the cause of the noise of the fan on the s900. It isn't just the one backplane but each shroud seemed to equally contribute to the noise. When all three grills were in place, the noise appeared to increase exponentially due to the vortices created. However, by installing a slower rpm ball bearing fan, I no longer am bothered by the noise and I still get lots of air flow. It has worked fine, same size as factory and slips right in. Hope this helps. Here's some of my prior post with fan specs I found: > ... > I just think that running a loaded Mac (or any computer) long-term without at > least one fan to keep air circulating would be an unreasonable risk I sure > wouldn't be willing to take. Sure, I guess if one has Gauge Pro running > constantly to monitor the processor, that's one option, but that doesn't > address the drives. One might even have one of those special internal temp > gauges which would offer more protection. But why not just exchange that > noisy, old-style ball-bearing (2,700 - 3,200 rpm & +- 49 cfm) Sunon (or > whatever you have), with a 'newer' quiet ball bearing or better fan of say > 1800 rpm and 25 cfm? Now that I've got the fan moving air in the right > direction :), overall air flow in the front and out the back appears very > adequate. Maybe come Summer, I might install a cpu fan, we'll see how temps > go. I do know that I wouldn't be w/o at least one fan to somehow move inside > hot air to the outside. > > While I am repeating some of my prior post now, I do believe this is a crucial > point focusing the problem. But after inspecting the fan, shroud, and all, I > believe it was merely a minor design flaw that they (UMAX) didn't account for. > And maybe it has something to do with the original air-in-from-back design > flaw that Will pointed out, but they never got it right thereafter. It is > definitely the grill and shroud which causes most of the noise you hear. When > I ran that same (what I thought was noisy) stock Sunon fan from a 12 volt > battery, outside the computer, and without the shroud, it ran extremely quiet. > This surprised me. Put it back in the shroud, sound increases quite a bit, > remount it on grill, and the noise levels increase exponentially. Hence the > problem! Put in a 1/3 slower rpm/cfm variety, noise problem goes away. > Ironically, even if you found the newest technology, ABSOLUTELY QUIET w/o > shroud, brand new 2,700 rpm with 45 cfm fan, it would become just as noisy as > before, once it was installed. In fact, if you mounted this same fan w/o a > shroud and cut away the grill, it would remain quiet (not that I would > recommend this). Unless you also have a bad fan, its the friction (vortices) > caused by the shroud & grill based on RPM & CFM that generates the noise. > > I for one would just not feel safe w/o some outside air movement into the > unit. And while there are many brands out there, here's the one I installed, > purchased at a local electronics supply, not RadioShock. For those not > familiar, some connector soldering might be needed, but it is still a fairly > simple task to change out these power supply fans, and very much worth it > ($11) for anyone who is annoyed with running that small turbo prop engine. I > can now run my computer all night in the same room without it being a bother. > That alone made it well worth the effort. > This is what I bought: > OD9225-12L 1800 RPM 25 CFM > About 2/3's down the page. > http://www.orionfans.com/dccoolfans.htm > > Now my newly acquired s900 whispers sweet nothings in my ear... If you can't find it locally, let me know and I can pick one up for you. Prices should be close to the same and shipping would only be a few bucks. Good Luck! Dave -- SuperMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | Service & Replacement Parts [EMAIL PROTECTED] | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> SuperMacs list info: <http://lowendmac.com/supermacs/list.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/supermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
