Making a truly silent HTPC

[Tweaker_McCharles]

I recently built a gaming / HTPC for ~ $1000 (see my profile). It includes a passively cooled Gigabyte Radeon HD 4850 (1 GB RAM), and uses a Noctua NH-U9B that is essentially silent.

The only thing in my rig that makes any noise is the case fans. I'm using Scythe SFF21D S-Flex fans (120 mm, 8.7 dB), but they still generate significant noise. I know it's compulsive, but I want this PC to be basically silent when it's 5 feet away, so I can read a book or whatever while it's on. Right now cooling is no issue (CPU always < 42 C, even when gaming).

To get even quieter fans, what should I go with?

The Scythe SY1225SL12SL "Slipstream" claims to be even quieter @ 7.5 dB for a hit in airflow:
http://www.newegg.com/Product/Product.aspx?Item=N82E16835185056

I found this Noctua fan being sold on another site (newegg doesn't carry):
http://www.endpcnoise.com/cgi-bin/e/std/sku=noctua_nf-s12.html?id=7mLYvYab

It claims that it gets < 5 dB with the Ultra Low Noise Adapter.

Would airflow be so terrible with one of these fans that it's not worth it? Is there a better option?

Thanks!

 

[13thmonkey]

have you checked temps with only 1 fan?

 

[Tweaker_McCharles]

I want to use 2 fans because of the design of my case. I need 1 to increase airflow behind the passive graphics card, and 1 to draw air around hard drives / CPU. Plus, if 2 identical fans are just too loud, 1 fan will still be noticeable.

 

[JohnnyLucky]

What pc case do you have?

 

[ainarssems]

connect case fans to 5V instead of 12V. That is what I have done. My PC is virtually silent except when I play graphics intensive games and 8800 GTS 512 MB fan goes up in revs as video card heats up. From lately played games it only happpens in GTAIV

 

[Tweaker_McCharles]

I have a Lian-Li C32B case, but I'm not using the fans it came with (see above).
I assume the 4-pin connectors from my power supply are all 12 V? Do I need an adapter / resistor to get 5 V?

 

[ainarssems]

What I have done I have pulled pin from fan connector from 12V position and put in 5V position. In Your 4 pin connector are 2 black wires going in(ground) in the middle, yellow wire (12V) on one side and red wire (5V) on other side. So from fan connector You pull out pin that goes to yellow wire and put it in the other side so that it connects to red wire.

 

[Tweaker_McCharles]

Ahhhh thanks a ton for the info. I had no idea it was so easy to fiddle with the voltage in standard cables. I'll go try that when I get home from work

 

[ainarssems]

Be sure to change wires on fan side on connector and not PSU. Or else You might forget about it and connect something else to that connector and blow something. If You change them on fan side of connector You are safe.

 

[Tweaker_McCharles]

OK, I'll keep that in mind. Though everything else I plan on having uses SATA connectors, so I don't think I could accidentally plug it into something needing 12 V.

 

[ainarssems]

Better safe than sorry. Never know you might be connecting some old HDD/ CD at some point and if You swap wires on PSU side and plug it in something it will feed 12V where it supposed to give 5V and something might blow - connected device or PSU or both. So to keep it safe swap wire on fan connector.

 

[Tweaker_McCharles]

Thanks again for the info--I'll definitely do it fan-side.