Super-simple PWM-to-3pin-fan adapter Note that this is absolutely as KISS as it gets. Particularily, you can kiss your RPM readings goodbye on anything other than 100% speed. If you want better, Tealc's http://forums.overclockers.co.uk/showthread.php?t=18421145 is for you. Note to future readers wi...

But the increased noise is so unlikely to be caused by back pressure -- a 1.3cm gap all around the perimeter of the case is adds up to a pretty large area, I'd guess at least as big as the fan impeller area, which means relatively low impedance. Small DC axial fans simply do not get louder with bac...

I will keep on wishing I had an anechoic chamber so I could do a quick test of my hypothesis of different fans reacting differently to enclosed spaces. The hobby scientist in me wants to know! *snief* It's an interesting theory but not one I would support after a dozen years of close experimentatio...

Mm, unfortunately the side directly opposite the fans is pretty much off-limits as far as major airflow goes. My projector sits there. I don't want to blow hotter air on it, and I don't want to suck in its exhaust either. (The PSU is far enough back that it blows air out way behind the projector - i...

ces wrote:Sound waves are quirky and complicated. No general testing in one particular environment can substitute for trial and error testing for your particular situation.

No but at this point of testing I'm thinking soddit & buy other fans to test with.

Looking at your pictures: -your intake holes have sharp angles But i came up with another thought: Decouple the top! Add some rubber between the top and the rest of the case. Make the gap 5-10 mm high, so you gain enough exhaust area between the case and the top. Judging from the pictures you did n...

The 2 120mm fans are intakes (running around 750 RPM), blowing nice cold air at the CPU and passively cooled graphics card respectively. The PSU is outtake, and obviously doesn't suffice on its own. Hence the 1.3cm gap all around for a surface area of circa 240 cm2. (Fans together are ~215 cm2 befor...

My case is a rectangular wooden block 55 x 37 x 17 internally, lying down. Two fans in one of the 55cm sides. The top is raised 1.3cm. Again: No top, no noise. - Top, noise. Seems like you build an instrument that resonates with the air-stream. Have you tested what happens when you add more weight ...

I should perhaps mention that one of my tests was to completely cover about two thirds of the side and leave about one third open. Exit diameter easily in excess of 500 cm2 but not in line with the airflow. I do not see a connection between the shape of my exhaust (not surprising to me, 1.3cm wide i...

As long as we're guessing spcr fan testing is totally fine. I see where your reasoning is coming from. But at the same time it strikes me as easy for someone with access to an anechoic chamber and SPL measurement equipment to take the existing fan testing platform and make it blow its air into a ta...

Just one thing to keep in mind : the only way to get a super quiet computer is to have as little restriction on the airflow as possible (in and out of the fans), because that allows you to run the fans as slowly as possible and as efficiently as possible (best noise/cooling ratio). Quite so. But wh...

What if you raise the top 5 cm just as a test ? 1.3 cm is not very much space, and I wouldn't be surprised if you got a lot of turbulence (might cause the noise). I have experimented with the top at different angles and heights just as you suggest (ruling out standing waves) and just as you say the...

How's the airflow affected ? I would assume that such a change in the noise pattern would cause some airflow change... What's your case btw ? My case is a rectangular wooden block 55 x 37 x 17 internally, lying down. Two fans in one of the 55cm sides. The top is raised 1.3cm. Again: No top, no nois...

What a thread title !! :lol: No, it's not flawed. It tests only one scenario, is of high quality, and results can be compared. The title was quite serious. If it leads to the development of fans that are only silent in free air, there is a serious problem with it! Have you tried your setup with onl...

I just spent yesterday trying to silence my home-built HTPC case further. I've had a semi-tonal noise (or perhaps best described as a sort of medium-to-lowfrequency pink noise) annoying me for a while, and decided to try to do something about it with padding. And when I opened the side panel... the ...

But here's an empirical observation: 2 identical noise sources (ie fans) should add up to +3 dB over one. But at the low levels we most often deal with at SPCR, the measured SPL never seems to add up to 3 dB. Most often, it's not much more than 1 dB. Maybe my pulled-out-of-my-ass hypothesis on (par...

This thread, however, is about fans =) I would submit that in this instance (the anomalous results of different fan configurations and brands on that particular heat sink) you really can't separate the two subjects. You have to admit, the fan performance results are non-intuitive.... don't you... t...

ces wrote:If you expect to be running most of the time near idle... the NH-L12 look pretty good to me.

I don't think anyone here proposes that NH-L12 is a anything but a good heatsink. (Notice how I'm trying to be diplomatic here to avoid further offtopic discussion)

This thread, however, is about fans =)

Yes, the 2 noctuas slightly outperform the single nexus on that heatsink in particular, so swapping them out would obviously be a Bad Idea(tm). But I was more interested in fan-vs-fan performance in my question. And I do believe the answer is "1 new Nexus outperforms 1 new Noctua where SPCR reader i...

Tibors wrote:According to this review http://www.silentpcreview.com/Noctua_NH-L12, it performs worse than the Nexus fan.

Ack, I didn't think to look at heatsink reviews. Thanks much for the pointer. A bit disappointing though; I thought they'd be better than that.

Well, when you overclock you normally try to undervolt as far as possible to reduce the heat generated. SPCR did exactly the opposite for purposes of simply generating as much heat as possible so they could actually see the difference between the bigger heatsinks. Conclusion: This test bed is about ...

If I can afford a naïve question: why, if Sandy Bridge is so efficient, the CPU temperatures are so worse than the previous ones (15-25°C more, with reference to the Athlon II X4 platform)? In addition to other responses, I should point out that the test platform is both overclocked and overvolted.

Mike, Question:

Among your untested fans, are there any Noctuas?

If no, do you have any plans to test them? Should we be email bombing them to send you samples? =)