In Search of Quiet PC, Will This Work Well?

[Anonymous Joe]

Just trying to build a little cheap PC that won't do much more than playback
Divx backups on a TV (I have most the parts, really just need a video card,
and some cooling stuff).

It's only going to be an Athlon 900, 320MB RAM, 40Gig single platter HD
(ATA/100), and either a 54x CD-ROM or DVD-ROM drive, and an Ethernet card
and Sound card. It will be Mid-ATX case size, since thats what the old
board is (Abit KT7-RAID that I've used for the past 3+ years).

Here's my idea for cooling: First make the PSU quiet. It has a rear fan,
which is 33CFM, 35dB, and I want to replace it with a 36CFM, 26dB fan
(80mm). The thought I just had as I'm writing this and looking at the PSU
without a fan in it is perhaps a very slow moving quiet 120mm fan, with some
sort of an 80mm-120mm adapter. I certainly wouldn't mind if it sticks out
somewhat, or even a few inches, if it will be much more quiet.

As for the Athlon 900, I believe I will be using the Thermaltake Tr2TT,
which is an 80mm based heatsink, with a 32CFM / 21dB fan, and is actually
rated to cool Athlon XPs all the way up to 3400+.

With this I don't think I should need a case fan. The PC would only be left
on for a few hours at a time. Would you think the same?

Also, any reccomendations for an alternative PSU fan, or the adapter idea,
or a quieter Heatsink/Fan would be appreciated. I will be using Arctic
Silver 5. It doesn't matter if the fan has LEDs in it or not, so long as it
is quiet and effective.

 

[Robert Myers]

Just trying to build a little cheap PC that won't do much more than playback
Divx backups on a TV (I have most the parts, really just need a video card,
and some cooling stuff).

It's only going to be an Athlon 900, 320MB RAM, 40Gig single platter HD
(ATA/100), and either a 54x CD-ROM or DVD-ROM drive, and an Ethernet card
and Sound card. It will be Mid-ATX case size, since thats what the old
board is (Abit KT7-RAID that I've used for the past 3+ years).

Here's my idea for cooling: First make the PSU quiet. It has a rear fan,
which is 33CFM, 35dB, and I want to replace it with a 36CFM, 26dB fan
(80mm). The thought I just had as I'm writing this and looking at the PSU
without a fan in it is perhaps a very slow moving quiet 120mm fan, with some
sort of an 80mm-120mm adapter. I certainly wouldn't mind if it sticks out
somewhat, or even a few inches, if it will be much more quiet.

Standard jet noise theory would say that the 120 mm fan should be 40
dB quieter than the 80 mm fan moving the same amound of air. There's
a catch (other than a badly-constructed fan). If you try to use an
adapter to expand the flow, you may wind up with the jet noise of the
original jet anyway because the flow has separated inside the
expansion. If you do try to gin up an expanding adapter (something
that shouldn't be all that hard), make the expansion as long as you
can handle structurally and aesthetically.

If you try such a thing and it turns out noisy, you may be able to
salvage the apparatus by lining the expansion with noise-deadening
material, because virtually all the noise generation will be taking
place inside the expansion collar. If you are on the noise-deadening
track, the long slow expansion is an even bigger win because it will
take most noise more bounces off the noise-deadening walls to walk out
of the adapter.

As for the Athlon 900, I believe I will be using the Thermaltake Tr2TT,
which is an 80mm based heatsink, with a 32CFM / 21dB fan, and is actually
rated to cool Athlon XPs all the way up to 3400+.

With this I don't think I should need a case fan. The PC would only be left
on for a few hours at a time. Would you think the same?

I would duct the fan as discussed by Dorothy Bradbury in another
thread. You can also google "ducted fans" and get all kinds of
advice.

Also, any reccomendations for an alternative PSU fan, or the adapter idea,
or a quieter Heatsink/Fan would be appreciated. I will be using Arctic
Silver 5. It doesn't matter if the fan has LEDs in it or not, so long as it
is quiet and effective.

120 mm fan is available standard and should be a big enough win.

RM

 

[Robert Myers]

Standard jet noise theory would say that the 120 mm fan should be 40
dB quieter than the 80 mm fan moving the same amound of air.

Make that 18 dB. The noise power goes as the inverse eighth power of
the area for a fixed volume flow.

RM

 

[Stacey]

Just trying to build a little cheap PC that won't do much more than
playback Divx backups on a TV (I have most the parts, really just need a
video card, and some cooling stuff).

It's only going to be an Athlon 900, 320MB RAM, 40Gig single platter HD
(ATA/100), and either a 54x CD-ROM or DVD-ROM drive, and an Ethernet card
and Sound card. It will be Mid-ATX case size, since thats what the old
board is (Abit KT7-RAID that I've used for the past 3+ years).

I'm shocked at how little cooling my "dvd"/digital image display system
needed to stay cool. I installed a zalman flower (rated to XP2000) on my P3
800 and cut a hole in the side of the PSU to pull some air over it. Removed
the grills from the PSU (80mm rear fan) and then put a 47 ohm 1 watt
resistor on the fan which made it -silent-. I have no fan on the CPU, only
the PSU fan for cooling. After a 1.5 hour movie the CPU temp was 45C, idle
it's at 40C or less. It's so quiet you can't even tell it's on with the
room silent sitting right next to it! So yea, I don't think you need a case
fan. Another noise maker is a video card with a fan, use a fanless card to
avoid that issue as well. An athlon 900 might produce more heat but still a
slow fan type CPU cooler should be plenty and might a ducted version.

Hope this helps.

 

[dhs]

As for the Athlon 900, I believe I will be using the Thermaltake Tr2TT,
which is an 80mm based heatsink, with a 32CFM / 21dB fan, and is actually
rated to cool Athlon XPs all the way up to 3400+.

Early Athlon processors actually use more power and so require more
cooling than the later Athlons. The earliest (Model 2) Athlon 900's
used 53W (typical) while the Model 4 900 used 45W. By comparison,
the Model 8 Athlon 1700+ (Thoroughbred A) used 45W. For the same
wattage, you get a processor nearly twice as fast.