Fans Are Noisy - Right?

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peteb

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Okay,

I think the major source of noise in my system is a little 6800rpm delta screamer sitting over my cpu heatsink.

It's spinning it's little heart out trying to get good airflow over my Swiftech370 heatsink.

Would a fan(s) - larger and slower, provide equal/better airflow quieter?

Okay a fan mounted laterally some distance from the heatsink is not likely to work well, but what about a ducted fan assembly?

Ducting is used occasionally in PCs for hotspot removal, but what about ducting for the cpu itself?

If you build a large (120mm) assembly and duct fresh cold(er) air from outside the case through a smaller outlet direct onto the cpu heatsink, will it do the same thing, quieter?

Curious on thoughts.

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Tempus

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Theoretically, a smaller and larger fan witht he same CFM rating cool equally. The problem is that you need the CFM concentrated over the Heatsink. If you were to buy a larger fan, it would be larger than the size of the heatsink, and some of its air would flow over the sides of the heatsink, doing nothing. Therefor less CFM of air would be cooling your heatsink. Thsi is why HSF fans are 60cm, the size of the top of the heatsink they mount on.

If you were to create flaps so that the air flowing over the sides of the heatsink were redirected at the top of the heatsink (in other words an extremely short duct)it should work.

If you decide to try it, let us know your results, I would be interested.

- Tempus fugit donec vestrum relictus tripudium. Autem amor praeterea magis pretium.
 
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ejsmith2

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There's about 4 different ways to do it, but 2 stand out. You can go down to the local hardware store/warehouse (read: Lowe's) and check out the plumbing section. Specifically, you're looking at sink traps and reducers. You can mount the 80mm fan to a reducer, and mount that to the heatsink. It'll cause a little torque, so you might need mounting brackets or a couple of toothpicks.

You can also mount the fan on your side panel, directly across from your cpu. This has the added advantage of pulling in outside air. Mount the reducer on the exhaust side of the fan, and cut it so it's about 1cm (or closer) from the heatsink.

Either way, you can run the 80/92/120 fan at 7V and get it a lot quieter.
 
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TheAntipop

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i like the idea of mounting one of those 120mm 130CFM fans on the outside of the case and ducting it to the heatsink, that would work great as long as your ambient temps arent too high.

Even a broken watch is right twice a day...
 
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peteb

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Yeah - I might try something really crude - remove the extraction fan at the back of my case (I still have a top blow hole and dual fan PSU) and run some vacuum cleaner hose in and ducted to blow in the HS. Bend radius will probably be an issue.

I could mount a frame with the shortest possible hoes length, and for the time being, some polythene, to reduce from the 120mm fan to ~50-60mm hose.

Ideally the hose and fan would be rigid, fulltime mounts. Smooth hose rather than vacuum cleaner hose (which tend to be ribbed) would give better airflow.

The ideal will be a ducted 120fan on the case side blowing direct, with no turns, just a concentrating flow 'nozzle'. Should get a fairly quiet (fan noise) 50-73cfm airflow. Next problem is that air might be noisy... Still cannot have everything.

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Tempus

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But the duct can't be too long. Elsewise by the time the air finishes going through it and finally reaches the heatsink, it won't be going very fast, therefore cooling poorly. the rule that more RPM=More cooling is true because the faster air is flowing over the heatsink, the faster heat is leaving it. Importing air from the side of your case through a duct to the CPU heatsink sounds a bit farfetched. I was talking about a duct/cone less than 1 inch long that would simply redirect excess air flowing over the sides of the sink because the fan would be too large.

- Tempus fugit donec vestrum relictus tripudium. Autem amor praeterea magis pretium.
 
Grizely1

Grizely1

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who cares about sound. Get some really sweet headphones, you don't have to worry about it. mine sounds like a freakin' washing machine.

From now on when someone asks you how fast your computer is, tell them your benchmark scores.
 
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Tempus

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Not all of us want to resort to wearing headphones every time we use our computers :smile: .

- Tempus fugit donec vestrum relictus tripudium. Autem amor praeterea magis pretium.
 
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peteb

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Thanks Griz, practical as always! :eek:)

Under other circumstances I would, however my wife complains when I cannot hear her shouting at me!

If I had a nice, dedicated basement to go and hide away in, I might not worry, but in an appartment it is a bit noisy.

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peteb

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I can see you point and I am not sure. 2 things.

It's easy to mount a 120mm fan to the case side and cut out a hole for it. The overall distance from inside edge of the fan to top of heatsink is not that great considering the reduction you are attempting to get. In my case maybe 10 cm or less. Even if it is 10 cm, you want to get from 120mm diameter to maybe 40mm diameter = 80mm reduction. This gives a 33 degree constriction on the duct, assuming no final pipe.

Much greater rate of constriction will probably have a really significant affect on airflow. I agree than a long duct would be bad, however a stteply constricted one would probably be worse.

I need to have a nose around and see what I can get.

If I were to do this, I'd probably use all other 4 fans in my case as extractors. They are Coolermasters at the moment. 4 of those, rated at 35cfm ought to help draw air in, over the cpu. I'd need to monitor everything else and make sure it doesn't get too hot though.

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louie2001

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I found this site on the Silverado not up on conversions so mabey someone will know the conversion to CFM's

http://www.noisecontrol.de/international/oversea/eng_info_page.htm

The Silverado offers a wide range of adaptable cooling power. If operated at nominal voltage, the twin fans move up to 42 m³/h, providing cooling power in the top range of air coolers, while still maintaining reasonable noise levels.

Rock out with your AMD out
 
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peteb

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Thanks,

I make that approx 19cfm (a cubic meter is approx 27 cubic feet since a foot is very nearly 1/3 meter).

So two 10cfm 12v Gamma28s = Silverado fan...

I think I can feel a project coming on....



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louie2001

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That's what I was contemplating about a project. Everyone
talks about them at Radio Shack but can't find any on their
web site. Will have to stop by there tomorrow and ask.

Rock out with your AMD out
 
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peteb

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on closer work I made it ~25.

2.54cm=1 inch.

1 meter = 39.37 inches = 3.28ft

1 cubic meter => equals 3.28^3 = 35.31cuft

the Silverado doed 42 cubic meters per hour, therefore .7 cubic meters per minute.

.7 cubic meters = 24.72 cuf/min

Luckily the japanese page for the fans quotes cubic meters (per minute) making life a little simpler...

:eek:)

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louie2001

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Well thats better than the 19 you came up with the first time now if I can just locate some in my area then I can puit some of my old heat sinks to good use and do some more cooling projects. Man cooling is becoming very adictive.

Rock out with your AMD out
 
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peteb

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yeah I know the first figure was rough. Hey it was only an approximation!

I have a computer - why should my mental arithmetic be any good? ;o)

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Tempus

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whoops. I calculated the Silverado for 49m/h. My bad.

- Tempus fugit donec vestrum relictus tripudium. Autem amor praeterea magis pretium.
 
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Tempus

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I know what you mean. I'm hankerin to design my own HSF!

- Tempus fugit donec vestrum relictus tripudium. Autem amor praeterea magis pretium.
 
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louie2001

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I agree,let the computer do the work that way you can use the noggin for more creative thinking on ways to improve the computer to do more work for you(just a thought)

Rock out with your AMD out
 
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