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PostPosted: Mon Jul 23, 2007 11:32 am 
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Joined: Tue Sep 20, 2005 1:21 pm
Posts: 412
Location: UK
Aris wrote:
This isnt some all passive low power system either. Its my main gaming rig, and has a total of 3 fans in it. stock psu 80mm fan, 120mm nexus, and a 92mm nexus. it plays every game i want on my LCD at native resolution of 1280x1024 at acceptable game detail.


It's a good point that running fans at low RPM makes them quieter. It also reduces the amount of airflow though. :(

You didn't mention what components your PC uses?

From the SPCR fan reviews your Nexus fans should be running at close to the specifications below:

NEXUS REAL SILENT CASE FAN D12SL-12 120mm

Voltage: 5v
Noise: <19dBA@1m
RPM: 490RPM
CFM: 16CFM

http://www.silentpcreview.com/article69 ... html#nexus

NEXUS REAL SILENT CASE FAN DF1209SL-3 92mm Fan

Voltage: 5v
Noise: <18dBA@1m
RPM: 570RPM
CFM: 11CFM

http://www.silentpcreview.com/article72 ... html#nexus

Now the Intel C2D E6600 @3.2ghz/ Nvidia 8800 Ultra system in an Antec P180 case that I linked to previously uses three Scythe S-Flex SFF21D 800rpm fans at 12v for cooling. (That's ignoring the PSU in it's seperate chamber).

Image
Falcon26's PC (C2D E6600 @3.2ghz, Nvidia 8800Ultra)

http://www.silentpcreview.com/forums/vi ... hp?t=41722

The quoted load temperatures for that system are quite good with those three Scythe fans. If you're prepared to run the components at just below their throttling temperatures there must be at least some scope to cut airflow and therefore noise. :)

SCYTHE S-Flex SFF21D (800 RPM) 120mm Fan

Voltage: 12v
Noise ~20dBA@1m
RPM:850RPM
CFM: 32CFM

http://www.silentpcreview.com/article69 ... html#sflex


This comes back to the original point of the thread:

If you were to take that same Antec P180 system (fitted with a 130w Intel Core 2 Quad QX6800 CPU and 130w Nvidia 8800GTX graphics card in order to meet the specs of the first post) on a warm summer day (room temperature 30c) could it be safely cooled under sustained full load using just the 27CFM of Aris's two Nexus fans at 5v?

I'd guess that it could work at idle but would start throttling significantly under load. :(


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PostPosted: Mon Jul 23, 2007 7:03 pm 
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Joined: Tue Sep 03, 2002 3:50 am
Posts: 43
Location: France
Aris wrote:
and even when you bleed all the air bubbles you can, you still have some left, and they do make noise.

No i dont have a link to how much noise bubbles make. But they are audible, and my air cooled rigs are not. So its louder than air alone.

I strongly disagree here.
You CAN bleed the bubbles out properly with an airtrap, the most popular one currently is the Swiftech Micro Res, a very well thought product that does exactly what it's advertised for. We're starting to see other kind of airtraps around... before that it was a DIY job (as i did). Once all the bubbles are out, a decoupled pump makes zero noise.
I recently built 2 systems with that mini reservoir, both are now very quiet (each had 2 fans + the PSU). Zero bubble in sight.
Again i repeat in such watercooled systems the only noise comes from the very few fans that are left, and the muffled HDD's.
Some people (typically in Germany) go as far as using huge radiators to cool them passively, thus achieving a zero fan setup.

And again, it's easier to cool a lot of hot components with a water system, and a properly mounted radiator, than trying to cool down multiple small hot spots at different places with slow moving fans (which wont allow high performance / overclocks, especially on hot days).
It's also easier to move away the cooling component, if it has to be noisy (radiator + noisy fans), to another room.


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PostPosted: Mon Jul 23, 2007 8:17 pm 
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Joined: Mon Dec 15, 2003 10:29 am
Posts: 2299
Location: Bellevue, Nebraska
i disagree, i guess we will just have to agree to disagree. your sense of "inaudible" seems to differ from my sense.

i can hear a decoupled enclosed in foam enheim 1048. i cant hear a nexus 120mm at 6v.


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PostPosted: Tue Aug 07, 2007 7:47 am 
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Joined: Mon Feb 28, 2005 4:21 pm
Posts: 2762
Location: NEW YORK WORD AND STUFF YEAH OK
zalman uses a much smaller eheim pump than that. size of pump in a zalman system has no effect on cooling. reserator makes less noise than a 120mm nexus at 5.5 volts (lowest setting my controller goes to)

pumps arent all the same. there are slightly noisier ones, ones that fail, ones that do not fail. additives help a lot. Water wetter brought down my pumps noise to inaudible at 1 foot in a silent room in the winter.

120nexus can be heard at 2 feet in a silent room.

thats about that.


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PostPosted: Tue Aug 07, 2007 2:27 pm 
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Joined: Mon Jul 16, 2007 2:35 pm
Posts: 808
Location: Greece
I think this debate is a bit of a civil war. Like it has been mentioned before heat is eventually dissipated by air. Not only that but both solutions use liquids to transfer heat to the radiator! Either phase change heatpipes or mechanically assisted water loops. So in both cases we are talking about different implementations of liquid assisted air cooling :)

In practice as silicone tubes used in water loops are more flexible than heatpipes, "water cooling" can benefit from a bigger, external radiator that can be cooled with lower airflow. So while a heatpipe fan, I have to agree that in practice water kits have the potential for greater cooling capacity at a given noise level. Someone could achieve comparable results by using a heatpipe set and external radiators however there are no standardised components of this kind in the market.

We also have to keep in mind that an external radiator is not always an option. In this case I think that heatpipe heatsinks are more efficient, they are better optimised for lower airflow than most water radiators fitting inside a case.

Something else to consider is other sources of noise like disk drives and PSU´s. A high end quad core system is unlikely to be paired with a 2,5 inch HD right? Often they are combined with a 10k rpm drive which can be a bitch to silence. Even if with their vibrations eliminated, their whine can be louder than a low rpm fan. In the same way, i don´t think it is easy to keep a PSU quiet and well colled when you constantly draw 350+ watts out of it. Passive PSUs have limited wattage ratings for a reason, and the ones that don´t often have poor reliability records.


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PostPosted: Tue Aug 07, 2007 2:55 pm 
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Joined: Tue Sep 20, 2005 1:21 pm
Posts: 412
Location: UK
ntavlas wrote:
Something else to consider is other sources of noise like disk drives and PSU´s.

...

I don´t think it is easy to keep a PSU quiet and well colled when you constantly draw 350+ watts out of it. Passive PSUs have limited wattage ratings for a reason, and the ones that don´t often have poor reliability records.


That's a good point. :)

You can get passive water cooled power supplies from a few manufacturers such as Alphacool and Silentmaxx. Koolance even offer a watercooled 1200w PSU but it comes as a kit. You'd need to ditch most of the kit and connect your own quiet water cooling to it.

http://www.koolance.com/shop/product_in ... cts_id=387

You can also get aftermarket modified power supplies that go up to 720w such as these ones:

http://edvextrem.de/english/produkt_psu_2fw.php

That could be good but they're not cheap and there are no reviews of them. :(

For the hard drives you could use the heat transfer properties of water to basically bury the drives in foam enclosures with just the water tubing and connectors coming out.

For example you could take the hard drive part of this article and connect it to your quiet water cooling setup:

http://arstechnica.com/news.ars/post/20 ... rives.html

You can get retail water cooled hard drive enclosures currently too of course. :)


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