Making the SLK3700AMB completely SILENT

acompeau · Post by **acompeau** » Tue Mar 09, 2004 12:12 pm

NOTE: started a new topic (was under the "Antec SLK3700 mid-tower Case: Ralf's Review" topic).

OK, this is driving me insane. I've currently got one running with a Zalman 7000 CPU cooler, a rear 120mm Panaflo fan, and a SilenX PS. Both front and rear fan grills are completely cut out. The hard drives are caged and isolated. Both fans are at 5V. It's still not quiet enough! While it's very quiet, I really want dead silence. I believe most of the noise I can hear is the sounds of air movement. some quick experiments with makeshift muffling of the rear exhaust fan seem to bear this out.

Here are the additional steps I've been considering (in order of extremity):

1. Constructing and attaching an exhaust "muffler".
2. Lining the whole case with DIY AcoustiPack (McMAster polymeric mastic + foam).
3. Putting the entire case into a custom cabinet with intake and exhaust ducted & muffled.

I think the cabinet approach is sure to work, but at considerable cost in time and materials (not to mention space). I'm afraid that the other options won't make it silent.

Any comments or suggestions on superior approaches? Am I wasting my time with anything but the cabinet? Keep in mind that I'm after total SILENCE here (as measured by someone with highly sensitive hearing at midnight in the sticks).

Thanks!

aphonos · Post by **aphonos** » Tue Mar 09, 2004 12:25 pm

acompeau wrote:OK, this is driving me insane. I've currently got one running with a Zalman 7000 CPU cooler, a rear 120mm Panaflo fan, and a SilenX PS. Both front and rear fan grills are completely cut out. The hard drives are caged and isolated. Both fans are at 5V. It's still not quiet enough! While it's very quiet, I really want dead silence. I believe most of the noise I can hear is the sounds of air movement. some quick experiments with makeshift muffling of the rear exhaust fan seem to bear this out.

Here are the additional steps I've been considering (in order of extremity):
1. Constructing and attaching an exhaust "muffler".
2. Lining the whole case with DIY AcoustiPack (McMAster polymeric mastic + foam).
3. Putting the entire case into a custom cabinet with intake and exhaust ducted & muffled.

I think the cabinet approach is sure to work, but at considerable cost in time and materials (not to mention space). I'm afraid that the other options won't make it silent.

Any comments or suggestions on superior approaches? Am I wasting my time with anything but the cabinet? Keep in mind that I'm after total SILENCE here (as measured by someone with highly sensitive hearing at midnight in the sticks).

Thanks!

Total silence will be impossible with moving parts. If you want total silence, pull the plug out from the wall.

If you want to pursue a virtually silent computer (ie cannot hear it from your working location) try unplugging/stopping fans one at a time or in groups (including the PSU fan) to confirm your theory of the fans/air causing the noise. Have you tried getting the fans to run at less than 5V? You may need to replace the Panaflo with a quieter 120mm fan, too. ie. a Papst 4412.

You mention HDDs (plural). How many? What model? How are they "caged and isolated"?

Do you have any kind of foam on (or against) the wall behind the computer to keep the fan noises from reflecting into the room?

Lining the case with some type of dampener or foam may help, but if the noise is airflow, not much will be gained from the foam.

acompeau · Post by **acompeau** » Tue Mar 09, 2004 12:28 pm

If you want to pursue a virtually silent computer (ie cannot hear it from your working location) try unplugging/stopping fans one at a time or in groups (including the PSU fan) to confirm your theory of the fans/air causing the noise. Have you tried getting the fans to run at less than 5V? You may need to replace the Panaflo with a quieter 120mm fan, too. ie. a Papst 4412.

Hmm.. I can try these. I have stopped the rear 120mm fan, and it is quieter. There is other "air whoosh" noise at that point, but my head is literally behind the case also. I'm assuming that's coming from the PS fan.

You mention HDDs (plural). How many? What model? How are they "caged and isolated"?

Sorry, single HD only. This one is an IBM/Hitachi Deskstar. I've got an aluminum HD cage that itself is suspended with McMaster 3/16" shock cord. I prefer this because the cage acts as a heatsink for the HD, but the shock cord isolates the whole thing from vibrating the case.

Do you have any kind of foam on (or against) the wall behind the computer to keep the fan noises from reflecting into the room?

No, I don't. I think the most reduction would come from putting on a muffled exhaust (my option #1 above). I'm happy to do this, but I'm concerned that the reduction achieved will not be adequate. In other words, if I'm going to need to make a cabinet anyway, building an exhaust that I don't end up using is a waste.

What I hope to find out from people who have done this already (maybe it was Bluefront or Edward Ng?) is if they would consider the result effectively silent while there is no background noise.

The current rig is effectively silent in the face of any background noise. I'd like it to be effectively silent when I'm trying to sleep. :

mrzed · Post by **mrzed** » Tue Mar 09, 2004 12:32 pm

I personally think you are just setting your goals too high. And the obsession has also gone perhaps a little too far. I say this as someone who has sensitive hearing, a 3700 AMB, and is about to move to the sticks, so I'm sure I will feel the same as you shortly.

A cabinet will no doubt also increase temps. How much the added fan noise needed will be damped by the cabinet is open to question.

I'm starting to be of the opinion I should get 2 computers. One in the current case that I can just keep at a reasonable sound level. the other a low-powered system with a quiet notebook hard drive and passive everything. The second one will make almost no noise, and can be left on all the time with very little power draw. It would also be small enough to integrate with the current desk, and use a little manual KVM to share peripherals.

ATM, I can't afford another computer, however cheap, so I make do with ghetto mods to silence the box I have. I do know that the limits of the current case configuration and hardware mean I am reaching the point of diminishing returns. Sounds like you are already there.

aphonos · Post by **aphonos** » Tue Mar 09, 2004 12:45 pm

mrzed wrote:I personally think you are just setting your goals too high. And the obsession has also gone perhaps a little too far. ...... I do know that the limits of the current case configuration and hardware mean I am reaching the point of diminishing returns. Sounds like you are already there.

I don't think you've reached the end of the line for quieting this rig. It may cost you the 3 E's (Effort, Expense, Evenings), but there is more you can do if you want to pursue it. Of course there is a lot to be said for learning to be happy with what you've got -- something I'm not always very good at myself (kudos to mrzed for this reminder

).

Getting rid of the IBM drive and replacing with a Samsung could drop your noise a bit. Though you've not mentioned HDD noise, so perhaps it is already inaudible to you.

Further undervolting the fans if you can handle the temps and they will start up reliably will help--as could replacing the Panaflo for a quieter 120mm fan.

Be careful adding a muffler. They can do serious damage to your airflow and hence your cooling. If you give it a try, keep an eye on temps.

If you search the forums on enclosure or cabinet you will find some folks who have tried a cabinet (including MikeC). Not many with glowing reports though.

Have you cut the grill out on the PSU?

Does your PC seem quieter/louder to you depending on which side of the PC you're on? Louder in front? Back?

Post by **MikeC** » Tue Mar 09, 2004 12:52 pm

an IBM/Hitachi Deskstar

Don't you find this too noisy? I would.

The Panaflo 120mm fan at 5V is probably too high. Drop it to 4V if it starts. Or change it for a 80L at 6V if the system stays cool enough.

Forget the internal damping for now -- it's the fans on the back panel making the bulk of the noise, and they'll be audible becasue of their placement on the back panel it even if you stuff the whole case with damping.

Does the PSU fan ramp up at all? If it does, put in a fresh air duct for it to keep that fan from ramping up. Tho this could be problematic with the front door of the case.

Do apply damping on the wall behind the PC. It will make an audible difference.

You may want to try damping behind the front door.

<edit> I see aphonos already posted some of the same comments. ah well, you should take the advice even more to heart!

Trip · Post by **Trip** » Tue Mar 09, 2004 1:01 pm

if you want silence, water cool, go with the zalman fanless case and a quiet HDD, or go Pentium M or a weaker setup...

Is the case on the floor or at ear level?

Does the case produce any vibrations? can any be felt with your hand resting on the case?

Maybe a tube of melmine foam would work that curved and connected from the exhaust fan - forget the enclosure, just use the foam. If you had this tube curve and then the exhaust air 3 inches from a wall of foam, it should remove a solid chunk of noise. Note: airflow would be cut, perhaps so much that the foam would need to be really thick to offer positive results (and there will always be the front fan with no dampening...)

acompeau · Post by **acompeau** » Tue Mar 09, 2004 2:06 pm

Thanks for all the suggestions guys. I'll try to answer everyone's questions in a summary:

- The front and rear fan guards have been completely cut out.
- There is no front fan at all (just the rear fan)
- The rear fan is mounted with those blue EAR grommets. I'm going to remount with 3/16 shock cord.
- The case is at floor level, resting on very plush & heavily padded carpet. It's not under a desk, which I think would help.
- There is some vibration felt by hand if you're touching the case. It's nearly indetectible, though. I'm guessing it's from the rear fan.
- The noise is *much* more apparent behind the PC than in front.
- If I'm directly behind the rear fan, I can hear some high-pitched whine and intermittent clicking. I think that damn 120mm fan is causing most of my irritation.
- The hard drive doesn't bother me at all. It appears to be sufficiently silenced by the suspension. I know it's not supposed to be a quiet model, but I think I just got lucky with the unit. It's just as quiet as my single platter Seagate Barracuda drives (another machine)
- The PSU fan never ramps up.
- I monitor my HD and CPU temps at all time. HD is usually at 27-31 C, depending on ambient. CPU varies, but is usually 43-47 C during use. This box is dedicated to Photoshop and can be very CPU intensive at times. It doesn't really get too hot.
- I cannot easily damp the wall behind the PC as it is a sliding glass door.

Solution comments:
- I'm leery of replacing the 120mm Panaflo with a Papst. I'd had bad experiences with them in the past (clicking up the wazoo). Maybe a 120mm Acoustifan instead?
- I'll try undervolting the 120mm fan some more. Right now it's attached to a Zalman MFSC, which bottoms out at 5V (I believe). I'll add an inline resistor to bring it down. I can always crank it up while starting the box, and dial it down after that.
- An impromptu "pillow" exhaust muffle test makes me think this might be good enough. I'm curious why a muffler would cause serious damage to air flow. This would be more like a baffle than a muffler, I suppose. I'm thinking about a large-ish 60 degree "bend" in the exhaust air flow using shaped foam laminate. Probably polymeric mastic + melamine + "egg crate" foam layers in a curve from the top of the case pushing air downwards (hmm.. picture == 1000 words).
- I'm very concerned with the added heat problem a cabinet would cause. I'm wondering if the cabinet approach would muffle sufficiently to allow turning the fan voltage up and remain silent, though.

I'll do a forum search for cabinets. I hadn't realized folks had tried full cabinets here before. Has anyone reviewed one of those overpriced "Coocoon" units from Denmark?

sorenbro · Post by **sorenbro** » Tue Mar 09, 2004 2:33 pm

The Papst fans you've had experience with have they been the 120mm fans, because most people find that the 80mm Papst can have some clicking issues while the 120mm do not suffer from this problem.

To quiten the harddrive even more you can buy a silentdrive and decouple it.
The Zalman CNPS7000 fan can be decoupled too, which is explained in other threads.

Trip · Post by **Trip** » Tue Mar 09, 2004 2:58 pm

A simple fix for the case vibration is quiet feet - Rubber boots stuck under the PC.

http://www.quietpc.com/ has them.

Thanks for the clarification, some of us need to read things twice

Out of curiousity, how hot is the PSU exhaust?

Nexus recently came out with some interesting 12cm fans.

Sunbeam Rheobus will allow you to reach sub 5V levels.

acompeau · Post by **acompeau** » Tue Mar 09, 2004 10:12 pm

Thanks for the suggestions, Sorenbro.

sorenbro wrote:The Papst fans you've had experience with have they been the 120mm fans, because most people find that the 80mm Papst can have some clicking issues while the 120mm do not suffer from this problem.

Yes, they were the 80mm fans. This was back before 120mm fans were readily available and I bought 4 of the Papst fans (at significant cost) only to be severely annoyed by their clicking. While it's good to hear their 120mm fans don't have the problem, I'm still leery (once bitten syndrome). I will try undervolting further and only explore alternate fans if that doesn't help. I've been really happy with the Nexus 80mm fans I bought to replace those Papst ones.

To quiten the harddrive even more you can buy a silentdrive and decouple it.
The Zalman CNPS7000 fan can be decoupled too, which is explained in other threads.

I already have some silent drive enclosures, but I don't use them. I don't like increasing my HDD temps if I can at all avoid it. I'm not really having a problem with HDD noise at this point.

I'll have to do a search on the Zalman 7000 decoupling. I hadn't realized that was done, although the older Zalman models all were decoupled from the heatsink part.

acompeau · Post by **acompeau** » Tue Mar 09, 2004 10:20 pm

Trip wrote: Out of curiousity, how hot is the PSU exhaust?

Nexus recently came out with some interesting 12cm fans.

Sunbeam Rheobus will allow you to reach sub 5V levels.

The PSU exhaust is usually just faintly warm. I really don't have heat problems right now. I think the CPU is shunting most of the heat in the system, and that appears to be exiting the case via the 120mm fan instead of the PS. The GPU doesn't produce a lot of heat (fanless model), since it's not a gaming box.

Maybe I'll order a Sunbeam Rheobus. I had a Nexus before the Zalman that made the most annoying buzz in the world when you turned voltages low for the fans. I think it must have been defective, because nobody interested in silence would have tolerated it. The Zalman has been great, except those toggles interfere with the SLK3700AMB case door (won't close all the way)...

I think I could do a museum exhibit with all the extra stuff lying around I've bought to make my PCs quiet.

Trip · Post by **Trip** » Tue Mar 09, 2004 11:36 pm

You had a nexus 12cm fan or a nexus fan controller?

lm · Post by lm » Wed Mar 10, 2004 1:48 am

I have to say my papst 4412f/2gl 120mm fan running at 5V or whatever the zalman fanmates minimum setting is is damn quiet. It's FAR quieter than zalman 7000 cpu cooler with fanmate minimum setting.

acompeau · Post by **acompeau** » Wed Mar 10, 2004 10:25 pm

Trip wrote:You had a nexus 12cm fan or a nexus fan controller?

Trip: Sorry for the lack of precision. It was a Nexus Fan Controller that buzzed. The Nexus fans I have are all very quiet, regardless of supply voltage (thus far).

lm: Thanks for the information. It does sound much quieter than the Panaflo I've got in there. Have you compared the Papst to a Nexus "Real Silent Case Fan" (1000 rpm @ 12V), an AcoustiFan™ AF120CT (1500-2000 rpm), or any other 120mm fans?

Gxcad · Post by **Gxcad** » Thu Mar 11, 2004 10:44 pm

Acompeau, I seek the same thing you do, and from my experience it is impossible with 120mm fans. The most air cooling you should have at all is a 80mm panaflo @ 4v deep within the case, MAX. To be honest with you I think even that is too loud if you seek dead silence. IMO, your best bet is to go completely fanless using FMAH's cpu cooling method, a Passive PSU, Zalman heatpipe and low heat vga, undervolting, and the quietest notebook drive placed in a carving rubber enclosure and placed on sorby (creative cooling as required), if the enclosure makes the drive too hot, I was thinking of having some copper stick out and out the slot covers at the back of the case, connected to a heatsink.

So basically, you almost pretty much have to go fanless, solidstate or at least notebook hdd isolated and enclosed, and if any fan, it should be one fan at the most isolation mounted and the quietest of quiet 80mm fans running at no more than 4v and deep within the casing to reduce escaped noise.

I will try it when funds and power tools become available!

-Ken

acompeau · Post by **acompeau** » Sat Mar 13, 2004 1:52 pm

Maybe I'll try some more radical things. I've got a few Nexus 120mm fans on order right now. I was thinking to bury a sinlge 120mm fan in the middle of the case, with ducting to direct the air flow.

I really don't think a single 80mm fan, undervolted, is going to supply enough cool air for the components in the machine right now. I've got a VIA C3 that's literally silent, but it's so unbelievably slow as to be useless. I use this box for serious Photoshop work, and it cannot be slow.

I'm beginning to think the fanless PSUs are a viable option at this point. I shudder to think how much money I've spent thus far on fans, grommets, sorbothane, case damping materials, and silencing miscellany. All for unsatisfying results.

It seems like I should just go the up front expensive route, but I'll try a few more things before I do that.