Sound Off: ULB Soundproofing

by Glenn Stone

The moment you've all been waiting for has arrived--the answer to the burning question, "Can we make a hotrod PC quiet?" And the answer is the subject of this article.

Those of you who have been following this series know that Monarch Computer Systems sent us a testbed system, a dual Athlon system. That system now contains, in terms of things that make noise, four Western Digital 36GB 10KRPM Raptor S-ATA drives. The case is a Lian Li PC-6070A that currently uses stock fans. Initially, this article was delayed because one of those fans had issues. To their credit, Monarch got me a new one as quickly as it could; I like good customer service. The power supply is an Enermax with the adjustable fan dial. Finally, the CPU coolers are stock AMD, which I have found from much experience to be a quiet yet effective way of dealing with the prodigious amounts of heat coming off an Athlon.

The real trick in this setup, however, is soundproofing in the case itself; Lian Li installed what appears to be AcoustiPack sound-absorbing foam in the top and side panels of the case, plus a rubber seal on the case door. As a former OEMer, I think it's cool you now can receive a quiet-ized case directly from the manufacturer rather than having to install the soundproofing yourself. Now, I didn't have a control case to compare with, so I explored what happened when you took the sides off completely and opened the front door of the case. Below is what I found; as a point of comparison, I include the numbers for the Dell Precision dual-Xeon workstation I recently reviewed.

            Open   Closed   Dell Precision
Front       47.5    45        47
Back        55      55        55
Top         47      45        45
Top Left    48      43        n/a
               (all values dBa)

Top Left is a new position for taking measurements, one I discovered empirically. It is 24" to the left, as in, side of the case you would take off to expose the PC cards, and 24" above the top front edge of the case. Using the sound meter, I discovered this was the point along the line 24" above the top edge of the case--user ear height, at which the most noise was observed. Other than turning the dial on the Enermax power supply down to the point where it is drowned out by the case fan (setting the fan on max raised the noise from 55 to 56dBa, a 20% increase), there is no soundproofing on the back of the case. As that is the major source of noise, the values were unchanged, but closing them made quite a bit of difference on the front. The 4db difference in sound--given that dBa is a log scale, this represents sixty percent less noise--is dramatic. Also, the system with this arrangement is as quiet as is Dell's dual Xeon system. Given that Xeons are known to be much easier to cool than are Athlons, this is an achievement in and of itself.

Given time and perseverance, we could have gone for a quieter fan in the back. Or, we could have done something as simple as placing rubber grommets on the fan mounts, which would cut the noise quite a bit more, and then installed Zalman coolers. Despite the not-quite-optimal setup, however, I think the preliminary answer to "can you make a quiet hot-rod PC" is an unequivocal "yes". The only problem is that although we can replace the case fans on the Ultimate Linux Box, I don't believe we will be able to replace the stock AMD coolers by press time. You see, no one yet makes quiet coolers for Opteron.

The folks at Monarch have been working hard on this little surprise, and I received an e-mail last Friday saying we will be able to get a custom Lian Li case into which to shoehorn this monster. We'll have the 3Ware/WD 4-drive RAID setup, the ATI Fire GL X1, an Audigy II sound card, a DVD/RW drive and a CD/RW drive, all atop a RioWorks dual Opteron workstation motherboard. We had to get the custom case because the standard case accommodates only a standard ATX motherboard; the workstation (with an AGP slot) boards come in only Extended-ATX formats. The only details left are making sure ATI comes through with a driver for the 64-bit Linux that an Opteron requires. Such is life on the leading bleeding edge.

In closing out this series and getting ready for the print article, I'd like to respond to some feedback I've received over the past couple of months, both specifically and in general. Last week, someone asked me why I didn't use the 160GB Maxtor S-ATA drives, which run at 7200RPM, instead of the 36GB 10k Western Digitals. My response is I am tuning this particular box for speed and not for drive capacity. If space is the primary consideration, then by all means use the Maxtors. Indeed, if I were doing the Ultimate Linux Storage Server, I would grab a 4U rackmount chassis, a 12-port RAID card, 12 of the 160GB Maxtors and have myself 1.7TB of high-speed data storage goodness. But that's not this year's article, which leads me to this conclusion: this isn't your Ultimate Linux Box, this is our Ultimate Linux Box, built with what is available right now. You may have something entirely different in mind for your needs. You may want a gamer's box; or a small, quiet router; or a LAN party box, something with a handle. You may want to run Linux on a PDA or set up the proverbial Beowulf cluster. Your budget may be $100, or maybe you just won the lottery. It's all up to you. That's the fun of Linux--it runs on almost anything. For this author, that's what really puts the Ultimate in Ultimate Linux Box.

The author would like to thank Monarch Computer Systems for its work in helping make this project reality. It's been fun.


Monarch Computer Systems


Glenn Stone is a Red Hat Certified Engineer, sysadmin, technical writer, cover model and general Linux flunkie. He has been hand-building computers for fun and profit since 1999, and he is a happy denizen of the Pacific Northwest.


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