Scythe 120mm S-Flex SFF21E is not really quiet

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visualguy
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Scythe 120mm S-Flex SFF21E is not really quiet

Post by visualguy » Tue Dec 30, 2008 9:02 pm

I just got a Scythe SFF21E (the 1200RPM 120mm S-Flex). I read a lot of recommendations for it claiming that it's quiet. It's not a noisy fan, but I wouldn't call it quiet. It's significantly noisier than the Lian-Li LI121225bl-4 which is the fan that comes with Lian-Li cases. I ran both the Scythe and the Lian-Li at 12V - I didn't try undervolting.

I believe it vibrates more than the Lian-Li as well since it managed to vibrate the metal grate that was screwed to it (it's a rear exhaust fan), while my Lian-Li fan doesn't do that.

The Lian-Li rotates at 1300RPM, by the way.

The only theory I have to explain this is that maybe the fan itself it quiet, but I hear the airflow. Based on my inaccurate "hand test" (place the hand behind the fan...) the Scythe pushes significantly more air than the Lian-Li (even though the specs suggest the opposite).

victorhortalives
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Post by victorhortalives » Tue Dec 30, 2008 11:04 pm

Yes, it isn't quiet at 1200rpm, but try it at 600rpm - excellent.

The other reason I like it is that it can run at very low voltages. Speedfan tells me that mine are now running at 410rpm (very lowest setting on the Zalman MFC1). I also have the 800rpm version and that stalls at anything below 600rpm (but is also very quiet at 600rpm).

If you want quiet at 1200rpm, then maybe a 1600rpm version undervolted may do the job.

echn111
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Post by echn111 » Fri Jan 02, 2009 2:57 pm

Sure you can undervolt it and reduce vibrations but it's probably covering up a mounting issue.

Vibration noise should be a non-issue with proper mounting, meaning that you should focus more on the actual noise the fan makes.

You should soft mount your fan or anything with moving parts otherwise you're leaving a lot to chance.

xan_user
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Post by xan_user » Fri Jan 02, 2009 5:19 pm

"WELCOME to SPCR!!"


Is it possible the noise is from a restrictive grill?
If the sythe is pushing more CFM than the old fan, maybe reducing the speed and/or removing any obstructions will solve your issue.

Modo
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Post by Modo » Sat Jan 03, 2009 5:04 am

echn111 wrote:Sure you can undervolt it and reduce vibrations but it's probably covering up a mounting issue.
No. It is normal for 120mm fans to become audible at around 700rpm, and it's only due to the amount of air they are pushing at that speed. The S-FLEX is very quiet below that speed, and still pretty quiet above, and that's why it is a recommended fan.

echn111
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Post by echn111 » Sat Jan 03, 2009 5:41 am

Modo wrote:
echn111 wrote:Sure you can undervolt it and reduce vibrations but it's probably covering up a mounting issue.
No. It is normal for 120mm fans to become audible at around 700rpm, and it's only due to the amount of air they are pushing at that speed. The S-FLEX is very quiet below that speed, and still pretty quiet above, and that's why it is a recommended fan.
Yes if he is complaining about vibration noise. And saying the S-FLEX has more vibration than the Lian-Li fan.

There should be "zero" (or close to zero) vibration noise if properly mounted.

p.s. I actually agree with what you're saying, but we're talking about two different things.

Modo
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Post by Modo » Sun Jan 04, 2009 3:21 pm

I was also talking about vibration noise. I have two 1200rpm S-FLEX hard-mounted in my build, and they are completely inaudible at any speed below 650 rpm. If there is vibration noise present, it only shows at higher speeds, where there is airflow noise already (so the source becomes irrelevant).

ntavlas
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Post by ntavlas » Sun Jan 04, 2009 6:39 pm

Excessive vibrations can be a sign of a damaged fan, even the best fan can be suffer damage during shipping/handling.

Are you sure they are running at a similar speed? Though unlikely, it is possible that Lian Li revised the specs of the case fan. My Lian Li came with a very good 1000rpm fan for example.

echn111
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Post by echn111 » Tue Jan 06, 2009 4:58 pm

Modo wrote:I was also talking about vibration noise. I have two 1200rpm S-FLEX hard-mounted in my build, and they are completely inaudible at any speed below 650 rpm. If there is vibration noise present, it only shows at higher speeds, where there is airflow noise already (so the source becomes irrelevant).
If you have vibration noise at 1200rpm, then you've got a problem. You can certainly cover up your problem by reducing rpm's to 600 or below therefore covering up inadequate soft mounting or a real problem with your fans, but that's all you're doing: covering up a problem. At 1200rpm, you "should" have audible fan noise (unless your case is well sound proofed), but you "should not" have any vibration noise that is transmitted to the case and clearly audible. I suggest you remount your fans and fix them and check if your fans or damaged as the previous poster suggests.

visualguy
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Post by visualguy » Sat Jan 10, 2009 1:43 pm

It turns out that my 120mm Lian-Li fan also vibrates its fan guard on occasion. I can't be 100% sure if it's the guard or the back of the case. The case is Lian-Li PC-A7110b (which is aluminum).

The fan is mounted with the usual metal screws.

blackworx
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Post by blackworx » Sun Jan 11, 2009 2:14 am

victorhortalives wrote:I also have the 800rpm version and that stalls at anything below 600rpm
Interesting. Mine was fine doing 360rpm @ 6V.

JaYp146
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Post by JaYp146 » Sun Jan 11, 2009 4:08 am

visualguy wrote:It turns out that my 120mm Lian-Li fan also vibrates its fan guard on occasion. I can't be 100% sure if it's the guard or the back of the case. The case is Lian-Li PC-A7110b (which is aluminum).

The fan is mounted with the usual metal screws.
You need to softmount every fan in a Lian-Li aluminum case, or it will reverberate like no other.

Mass loading the side panels wouldn't hurt, either.

visualguy
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Post by visualguy » Mon Jan 12, 2009 11:32 pm

JaYp146 wrote:
You need to softmount every fan in a Lian-Li aluminum case, or it will reverberate like no other.

Mass loading the side panels wouldn't hurt, either.
Vibration is very hard to trace. I'm pretty sure now that the offending party is the the metal strips (not sure what they're called) which cover unoccupied PCI slots. The top is screwed in, but the bottom can move back and forth a little bit and make noise as a result of vibration.

I was going to try to put something there to stop the PCI slot cover from having any play, but instead I just undervolted my fans so that they don't cause vibration. The fans are also much less noisy now, of course.

I actually prefer steel cases to aluminum cases for a number of reasons, but I just wasn't sure which full-tower steel case was good when researching this. I don't actually like the Lian-Li that much, and not just because it's aluminum. The design of the case is such that removing things like some of the fans (front bottom) or the top rear hard drive cage is major surgery, including in some cases having to remove the motherboard to access the screws - a really bizarre design from that perspective.

I'm still looking for a good full-tower steel case.

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Post by victorhortalives » Tue Jan 13, 2009 2:53 am

blackworx wrote:
victorhortalives wrote:I also have the 800rpm version and that stalls at anything below 600rpm
Interesting. Mine was fine doing 360rpm @ 6V.
I just checked it again and the lowest it will reliably start (maybe that is the problem) is 585rpm. I can run it lower once it has been started.
It is on a Fanmate 2 running from a 90W Pico PSU. I haven't measured the actual voltages. (I also had the same problem when running it from the ZM-MFC1 /Corsair HX520 combination)

On my other PC, the 1200rpm fans run at 417rpm and 424rpm from a ZM-MFC1 running from a Corsair HX520.

davidh44
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Post by davidh44 » Mon Feb 09, 2009 4:45 am

My 1200rpm S-Flex 120mm fan doesn't start up when connected to a 5V lead.

samuelmorris
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Post by samuelmorris » Thu Feb 19, 2009 3:32 am

1200rpm is high for any 120mm fan if you want silence. Lian-Li fans (the black ones) are especially good for low vibrations and relatively low noise, but don't seem to push at much air for the same speed, so for a true comparison, cut the speed of the Scythe a bit. I would also agree that the difference between <900rpm and 1000+ with an S-Flex is considerable.

Bruce Banner
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Post by Bruce Banner » Tue Mar 24, 2009 8:14 pm

try an enermax magma 120mm. I have 3 and at full speed you can't even hear bearing noise with your eat to the fan.

christpunchers
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Post by christpunchers » Sun Mar 29, 2009 5:27 pm

Strangley enough, I'm on the same boat as you.

I have the LianLi A71. I think it's a very similiar case to the A7710 that you have.

I wanted to replace the stock Lian-Li fans. They're very quiet at 12v, pushing a moderate amount of air. Through the advice of a friend I've chosen to try the Slipstream 120mm @ 1200rpm. It pushes out a lot of air, but it vibrates a lot more and I can hear the motor noise. But at 1000rpm using a resistor it's almost silent and not audiable at all.

Can anyone recommend good 120mm intake & exhaust fans? I will have some obstruction before the intake (filters and grille), what's the best fan to suck in enough air?

The exhaust I will have no obstructions, so I guess I could go for something really quiet but I don't want to lose out on the ability to draw out heat either.

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Post by aristide1 » Sun Mar 29, 2009 5:30 pm

When I took the fan out of my Tuniq Tower I plugged it in and turned up the control to hear the fan as a stand alone item. I noted 2 distinct points on the control where the fan vibrated. Above or below those 2 speeds it was smooth. I marked the 2 spots on the control and I avoid them. FWIW.

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