Quieting pump noise

The alternative to direct air cooling

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N7SC
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Quieting pump noise

Post by N7SC » Sat Aug 18, 2007 6:39 pm

I have a Swiftech cooled system, using their MCP 350 pump. The whole shebang, including the pump, is mounted on the removable motherboard tray of a Lian-Li PC-A10A (yes, pump, reservoir, and radiator all come out on the tray). The pump is mounted with two very loose bolts/screws going through the Swiftech supplied rubber isolation grommits on the pump, and the heads of the screws are isolated from the m/b tray with little silicone fan mounting washers. The pump sits on a block of Petra's Gel-Stuff from Petra's Tech Shop.

The pump noise is the loudest noise in the system. How can I mount it to decouple it even more from the motherboard tray? And would stiffening the m/b tray, like by epoxying a sheet of 1/4" plywood or MDF to the bottom of it, help quiet it down?

Also, can I surround the pump with foam blocks to try to enclose the noise source, if I leave a bit of breathing room for heat to dissipate?

Have also posted in the cases/damping forum about stiffening/mass-loading the case itself to help reduce noise.

Perhaps I should say that the system is not very noisey at all, but I would like to quiet it down as much as possible.

zoob
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Post by zoob » Mon Aug 20, 2007 1:24 pm

Is it the woosh noise that you're bothered about? Try undervolting it a bit, or changing the top with an Alphacool or Petra top. The added mass seems to dampen the sound a bit.

N7SC
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Post by N7SC » Fri Aug 24, 2007 5:09 pm

Actually it is more of a mechanical hum or buzz.

Was wondering if the mounting screws are transmitting sound to the motherboard tray. Maybe I can rig up some kind of elastic mount to hold it in place. Also considering eDead or something heavy to mass-load the back/bottom of the motherboard tray and help damp vibrations there.

If I have to box it in a bunch of foam, will it hurt it by confining the heat it produces, or is most of its heat extracted in the coolant loop anyway?

Aris
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Post by Aris » Fri Aug 24, 2007 6:42 pm

you have just discovered the single biggest reason why air is better than water for silencing. Its the main reason i switched back to air from watercooling.

It is possible to reduce this noise from the pump, but very difficult to completely eliminate it, if not impossible depending on the pump used.

It MUST be completed suspended from the chassis. Pumps have a LOT of vibration. I remember having my W/C rig, listenig to it thinking "man thats loud, i wonder whats causing it" and then pick the pump up in my hand in the noise instantly vanish.

Along with suspending it, it will also need to be dampened by encasing it inside foam insulation, or inside a box lined with foam insulation.

So yeah, put the pump in a small box lined and suffed with foam, and then suspend the box somewhere inside the case. Then it will either be "quiet" or if you have a quiet pump from the start you may actually be able to eleminate the sound all together. But then now you have the add'd hassle of not having a completely solid system. Meaning if you ever go to move the case around you have to now be extra carefull because something inside it is free to "bounce around" and not bolted down.

The only other way ive ever seen a pump silenced is to remove it from the case and mount it somewhere outside the system. But then now your system isnt mobile anymore, so if you ever want to go to a LAN game or you move its either impossible or a huge pain in the ass to do.

subsonik
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Post by subsonik » Sat Aug 25, 2007 3:55 am

Aris, it is possible to silence a water pump completely. I am running an undervolted Eheim 1048 - it runs on 65V / 20Hz instead of on 230V / 50Hz. It's not even softmounted, and I can only hear it when it's completely quiet in the neighbourhood, and I'm putting my ear right next to the pump. The 20Hz hum is so low that it's barely audible.

However, it's not easy to accomplish. The trick requires some electronics for the undervolting part, and it doesn't work with all pumps. I'll post schematics and pictures in this forum as soon as I have some more time :)

Aris
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Post by Aris » Tue Aug 28, 2007 11:49 pm

subsonik wrote:Aris, it is possible to silence a water pump completely. I am running an undervolted Eheim 1048 - it runs on 65V / 20Hz instead of on 230V / 50Hz. It's not even softmounted, and I can only hear it when it's completely quiet in the neighbourhood, and I'm putting my ear right next to the pump. The 20Hz hum is so low that it's barely audible.

However, it's not easy to accomplish. The trick requires some electronics for the undervolting part, and it doesn't work with all pumps. I'll post schematics and pictures in this forum as soon as I have some more time :)
I had an eheim also, cant remember if it was the 1048 or the step up from that (1280??), its been so long.

Anywho, i was able to get it to be very quiet, but there was always an audible "chug chug" low frequency noise that i was never totally able to eliminiate. I didnt have it completely suspended though(only soft mounted and encased in foam), mostly because i didnt want something dangling around inside. Too unstable for my likings.

Im sure if you put a lot of work into it, you could possible rig something up, but considering i could get the exact same performance with a lower system noise signiture for less money and less hassle with air.

For me it was never about the overclock, which is why i see most people using W/C setups, it was to try and achieve a quieter system, and in that aspect alone, air is superior.

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