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ARM Systems StealthPC P4-3.2 Powerhouse

Jan 21, 2004 by Mike Chin

Stealth UltraQuiet PC - P4-3.2
ARM Systems
US$2700 preloaded with Windows XP Pro

It has been well over a year since our first quiet prebuilt system review, on the Stealth XP 2000+ PC by ARM systems. We gave it two thumbs up for excellent performance and very low noise, and concluded that it is "an attractive, viable option for those who seek a ready-made quiet PC." Since that time, we have added a few more prebuilt and barebones quiet system reviews. Awareness of noise as an issue among PC makers has certainly risen, but you still can't go to any system builder, small or large, and order or buy a quiet PC. The number is growing but it is still pretty small.

In the meanwhile, ARM Systems has been quietly expanding and improving their StealthPC line. Their approach has not changed dramatically. To reiterate the summary from the original review,

ARM Systems is a veteran amongst quiet PC makers, having offered their line of build-to-order Stealth "Noise-Reduced" PC systems for three years (over four years now). A systems integrator established in northern California since 1986, ARM Systems does business with customers all over the US, both corporate and private. Their Stealth systems were introduced in response to consumer demand, and have been refined continuously. Due to this steady evolution, ARM Systems say that their current offerings are quieter than the original model, despite being many times more powerful. Both AMD and Intel processors are offered in their Stealth line

The subject of the current review is a loaded-to-the-gills P4-3.2GHz system with just about every performance feature you can throw into a desktop PC. The SPCR question about such a powerful machine, of course, is whether it can really be quiet.

A post was made in the SPCR forums about a visit I made to ARM Systems' facility in late November last year:

I was in SF briefly after Comdex last week to visit my parents. ARM is only ~50 mi north of where they live, so I took a drive up for a quick visit. They were really busy but took a bit of time to show me around. They have a 10,000 sf facility. They showed me a fully loaded P4-3.2G system being tested for a game development customer. I mean LOADED to the gills:

  • 2 GB of very high speed RAM
  • 4 HDDs,
  • ATI-9800XT,
  • 24-bit sound card
  • 2 optical drives
  • etc.

They said it had been running a commercial burn-in program for 48 hrs -- the temps were amazingly low AND I could only hear the thing whirring quietly from about a meter away after they turned all the printers and the HVAC system off. I guesstimate 25-28 dBA/1m. Amazing thing is that it is in an Evercase 4252 case -- with 120mm back fan -- which seems too small to handle all that... but they have engineered it somehow!

I hope a review of this model can happen soon. It's possible that my guesstimate of its noise is low because of the higher office ambient noise; I'll know for sure when I have it in my lab. In any case, I think it could fairly be called the silent answer for gamers. But 4 drives?!

The PC on hand is not identical to the one described above, but it is not far off. The main difference is the amount of RAM (there's less) and two hard drives instead of four. Here are the details:

ARM UltraQuiet Mid-Tower w/NS Acoustic Foam / RamAIR Duct / 2x120 Fans / Black
Power Supply
ARM Factory Modified Zalman 400W APFC
Intel D875PBZLK: P4 800FSB 2Ch DDR400 w/SATA-R

0, 1 / Gb LAN / USB 2
Intel P4 3.20GHz HT 800MHz FSB - w/512k Cache
System Cooling
STEALTH Level-5 XtremeQuiet: 3x HeatPipe CuHS / UQ

fans / Acoustipack Foam
512MB total: Two (2) 256MB HyperX DDR400 PC3200 CL2 Low-Latency SDRAM DIMM w/Heat-Spreaders
HDD Controllers
Onboard 2-Ch SATA w/RAID 0 & 1 (2xHD) + 2Ch

Hard Drives
Two 80GB Seagate Barracuda SATA V - 8MB Cache
Video Card
256MB DDR ATI Radeon 9800XT w/SVGA/DVI/TV-Out
DVD Drive
16xDVD Sony
52x24x52 Sony IDE CDRW
Other Drive
3.5 Floppy
7.1 Creative SB Audigy-2 ZS Platinum w/2xFireWire &

Front Panel I/O Breakout
Operating System
Windows XP Pro SP1, fully updated
ARM Gold 331 Limited Warranty Program 3 YR Parts/1

YR Onsite
US$2700 configured with Windows XP Pro

The ARM Systems StealthPC line is infinitely customizable with their EZ Configurator ordering system. The review sample is obviously a high-end product with leading-edge performance. Of course, you are curious about what this beast looks like. In a word, it's a sleeper:

It's a handsome, black unit based on a customized variant of the Evercase 4252 case. A new blue logo distinguish the ARM Stealth PC.


The review sample came packed in a very substantial box, especially considering that it only contained the PC -- I'd specifically asked that keyboard, mouse and monitor not be included. The shipping weight was an amazing 49 lbs. (over 22 kg.)

The packing is also very substantial as shown by the photos below. The foam pieces are custom made with an industrial foam injection molding machine at ARM Systems' facility. It all fits tightly together so that nothing shakes or moves within the box, yet is cradled in shock-aborbing material and is easy to unpack.

Unpacked StealthPC explored by curious Ms. Kitty Kat, who finally gets a mention in SPCR.

Not surprisingly, the PC itself is very hefty: It weighs 38 lbs. or over 17 kg. (Ms. Kitty refused to lend a helping paw, despite my cries of help.)

ARM Systems have shipped thousands of Stealth PCs and learned many lessons along the way. Their rules of thumb to ensure shipping survival, according to Steve Collins of ARM Systems:

"The process of shipping a system thousands of miles, or sometimes even locally can place a computer system under more g-forces and shock stress than most customers, or some vendors, ever realize. To deal with that kind of abuse, we use double-walled heavy weight custom designed shipping boxes and we own an industrial foam injection molding machine right here in our shop to ensure the systems are safeguarded in transit. All of our boxes and foam systems are designed and tested by 3rd party freight experts outside our company and then stress tested to exceed national shipping standards by size, weight, and content. The reality is that we work too hard to design and build the StealthPC to not have it show up in pristine condition.

"Secondly, all component products inside an ARM StealthPC are designed to survive very heavy abuse by the freight carriers. Extra structural supports are installed inside to lock down heavy video cards. Massive heatsinks are bolted through the motherboard and cross-braced on the underside to ensure the mainboard is safe and the CPU cooler stays solidly put. All other items inside are tied down, secured and otherwise gorilla-proofed."

ARM's basic approach to building StealthPCs has not changed, which is a good thing, in my view:

  • Use high quality components. Warranty service costs eats up whatever can be saved on buying slightly cheaper but lesser quality components. Particularly important as quieter PCs tend to run a bit warmer, which causes higher component stress.
  • Ensure safe cooling in summer weather (up to 30°C or 85°F). Their noise target for the hottest condition is


The system arrived with Windows XP Pro fully loaded and totally updated; at least it was on the day that I plugged it into my network and checked Windows Update. The OS worked without any glitches that I could detect. This is impressive. The number "fixes" required for Windows XP to be safe and up-to-date runs into many dozens and the size of data probably runs well over 100 MB and it is not uncommon to spend hours doing this dreary task. It's also not uncommon to run into glitches with updates. I am told that ARM Systems maintains a huge specialized cache system on their web access server so that downloadable upgrades from Microsoft and other are available at LAN speeds rather than web download speeds.

Motherboard firmware and related software for Windows all seemed to be installed and up to date as well. The preloaded software included many associated with included hardware but also utilities that are not normally a part of Windows or hardware:

* Power DVD

* NTI CD-Maker

* BurnIn Test

* Creative - a huge number of titles associated with Audigy 2ZS Platinum

* WinZip

All of this software worked perfectly well right from the start. Again, this may not be unusual, I have experence with less than ten new completely prebuilt systems, but I found it really pleasant and impressive that all the software in the system worked so well straight out of the box.

Naturally I marvelled at the sheer speed of any applications I loaded and tried, including...

  • Adobe Photoshop
  • Adobe InDesign
  • Macromedia Dreamweaver
  • MS Office
  • PowerDVD
  • NTI CD-Maker
  • Creative-related sound apps

My impression after a week of casual use was that this is a very fast, quiet machine. In normal use, this StealthPC does not change its noise output much, staying pretty quiet most of the time. It's only under intense video and CPU stress that the fans speed up a bit and I become aware of increased noise. More on noise later, with SPL measurements.


Front Panel

Despite the absence of any colored trim to offset the expanses of black, the front panel has panache, perhaps lent mostly by the prominent technical-looking Sound Blaster Audigy-2 ZS Platinum control I/O front panel. This is the top model from SB with 24-bit/196kHz DAC and stereo playback, a host of functions and a huge package of software that would require a dedicated 20,000 word review to cover fully. Suffice it to say that it is one of a very small number of contenders for top-dog status among consumer audio cards. The Sony DVD and CDRW drives stacked below the SB front panel don't hurt the serious look of this PC, either.

Great Bezel Design

In case there's any doubt, aside from the absence of a grey colored trim around the top half of the front panel, this bezel identical to the in the previously reviewed Stealth XP2000+ PC. Many readers will already know that the case is an Evercase 4252 variant, which has the best noise-impeding, yet high airflow bezel of any case we've come across.

In case anyone missed them, here are the pictures of the front bezel and intake vent from the last review.

The front chassis metalwork on
the right is the same in this P4-3.2 system; the main difference is the use of a 120mm fan instead of the 80mm fan in the StealthPC XP2000+ shown here.

Wide open front intake vents provide excellent airflow yet prevent a direct escape path for noise .

The vertical grooves in the bezel are actually ventilation slots for the front air intake. The center shows the bezel removed. You can see just how open the intake vents are. There is also a large hidden opening at the front bottom of the bezel.


The back panel is fairly conventional, except for the square holes in the 120mm grill for the back fan, which presents very little impedance to the exhaust airflow. This 120mm exhaust fan capability is a relatively new variant of the Evercase 4252 mid-tower case. A black Zalman ZM400A-APF modified with a Panaflo 80mm low speed fan is visible.


The inside of the case is completely treated with AcoustiProduct damping, which is about the best marketed to the computer industry. The heavy damping material just about everywhere it can be applied except on the right cover behind the motherboard tray, which is a solid piece that extends across the entire right side. There no room between that inside wall and the right cover for any significant layer of damping foam to be installed; the AcoustiPack material is at least half an inch thick. All this acoustic damping helps to absorb internal noise.

RamAIR Duct for fresh cool air to the CPU and AcoustiPack damping for noise reduction

Gap between right side panel and right inner wall of case is extremely small; no room for damping material -- and probably no need either, given the double-steel wall.

Note that the side vent has a tubular flared duct, which ARM calls a RamAIR Duct. When the left cover is fitted back in place, the duct is positioned perfectly over the CPU cooling fan with no more than 1 cm gap. This ensures that the CPU/heatsink gets the benefit of cooler outside air. The system ships with thumbscrews that hold the cover in place, but once off, the 2 green tabs visible on the back (left) edge allow the cover to be removed. The fit is very tight, and some effort is required to slide the side panel backwards so it can be lifted off.

The vertical PCI retention bar is impossible to miss. It ensures that the heavy ATI Radeon 9800XT VGA card, equipped with a Zalman HP-80C VGA heapipe cooler (follow the link to our review of an earlier version of this HS) plus integrated 80mm fan, is held securely in place. The retention bar also adds rigidity to the case, which is probably helpful given the system's high 38 lb weight. I won't go into any real detail about the ~US$500 Radeon 9800XT. Suffice it to say that this latest top-of-the-line VGA card from ATI features an amazing 256 mb of RAM, has built-in dynamic overclocking (called Overdrive) and appears to be the darling of extreme gamers everywhere.

Above the big NB heatsink on the Intel motherboard is the Panaflo 92mm low speed fan mounted atop a Thermalright SP94 copper heatpipe heatsink (follow the link for our recent review). Note the Zalman Fanmate1 fan speed controllers mounted on the frame of the fan with Velcro and the blue heatspreaders of the high speed 256MB HyperX DDR400 CL2 SDRAM, two sticks for dual channel memory operation .

Here's another look at the ATI-9800XT VGA card cooled by the Zalman HP80C heatpipe cooler and its dedicated slim 80mm fan. (Photo taken with PCI card retention bar removed.)

The photo above shows the two Seagate Barracuda Serial ATA V hard drives, mounted with EAR elastomer vibration damping grommets in the slide-and-lock mechanism 3.5" removable drive bay. There is no metal-to-metal contact between the hard drive and the chassis. This is the same HDD noise reduction technique used in the first ARM System review sample. The SATA drives are in a RAID 0 configuration, using the built-in RAID controller on the Intel D875PBZ motherboard, arguably the best for the P4 with hyperthreading. The Automatic Acoustic Management (AAM) came set for the minimum seek noise on these drives. Note how the bottom drive is mounted upside down. This was done, according to Steve Collins of ARM Systems, to maximize the distance between the two drives for better cooling.

The two 120mm fans used, one for intake in front and one for exhaust in back, are both connected to motherboard fan headers through Zalman Fanmate 1 voltage controllers at reduced setting. Neither fan is identifiable as they do not have any markings on them. They are quiet at idle, with a bit of bearing chatter that is audible from up close, and appear to be thermally controlled by the motherboard, as they ramp up in speed as the system heats up under load.

The Panaflo-fan modded Zalman ZM400A-APF is a heavy-duty 400W PSU that starts quiet and stays that way even at the maximum power draw of this review system. Its appearance and Zalman's specifications indicate that it is most likely a variant of the Fortron-Source 400 APFC PSU. However unlike previous F-S variants we've examined, this one is said to be extra efficient: 75% is the minimum AC/DC efficiency with 230VAC input. This is a significant improvement over the typical 70% PSU efficiency and should help in reducing the total heat in the system. With the Panaflo 80mm low speed fan swap, the Zalman PSU is very quiet, and does not ramp up much at high load. NOTE: ARM warranties all components directly, including this modded PSU, which would probably lose the Zalman warranty.

The Sony DVD and CD-RW optical drives are not really quiet when accessing data, but certainly not the worst I have heard. The maximum access speed can actually be limited with software (such as that incorporated in Nero) to keep the noise down. Suffice it to say they are silent when not being accessed (which is most of the time for most of us) and hardly add any noise at all when playing DVD movies or music CDs.


Measured SPL

Sound pressure levels were measured in a small carpeted room (10'x10'x8') with a calibrated B&K sound level meter (model 2204) capable of reading down to below 0 dBA. The PC was set on a 20" tall stool near the middle of the room and the SLM positioned or held in various spots 1 meter away from the nearest surface of the PC case. The ambient noise during the acoustic measurements was ~18 dBA, well below the level of the PC being measured so that it did not affect the readings. Each measurement was performed after at least 15 minutes continuous use in the specified activity.

Mic 1m from
System Activity
CD/DVD play
HDD Peaks
* All numbers are in dBA @ 1 meter

During CD/DVD play, there was no other load on the system.

* Folding refers to the [email protected] client software, which places the CPU at 100% load. It does not generate the highest heat but is a good test for long term hard use.

* CPUBurn generates the highest heat levels of any CPU stress program. An extreme test.

* HDD peaks is the peak noise during hard drives defragmentation.

Listening Analysis

Subjectively, the ARM Systems StealthPC P4-3.2 is very quiet at idle. It compares favorably with any normal production PC, including quiet Dells. It is very unobtrusive, though not inaudible in a quiet room. Overall, it is not much different from the first Stealth XP2000+ system reviewed in late 2002. Given the massive increase in sheer wattage under the hood, this is no small feat.

The maximum noise is from the rear where both the PSU and case fans are mounted, the norm for standard box PCs. The simple expedient of attaching a large piece of soft foam on the wall behind the PC will lower this noise by several decibels. This is not obtrusive when the PC is under a desk; it is a noise-reduction technique practiced by many PC silencers. As mentioned previously, DVD or CD playback adds little or no noise overall.

At full load, the front and rear 120mm fans speed up by a couple hundred RPM; the details are recorded in a graph below. Noise rises by several decibels; most of it is the relatively benign whooshing of airflow turbulence. This is where the current system differs most from the previous ARM Stealth; when pushed hard, over time, there is a gradual increase in noise (to still a very modest level) as the case fans ramp up to move the added heat out of the case. Considering that the total CFM through the case is probably more than double compared to the 80mm Panaflo-L equipped 2002 model, the increase in noise at max load is modest, indeed.

The loudest noise comes during HDD seek/write. The clickety-click noise of the Seagate Barracuda SATA V drives is mostly muted by the EAR soft grommet mounting and by the AAM, but it is not completely eliminated. In this regard, it is Seagate who is responsible for the noise change: The Barracdua IV was a quieter drive, but it is no longer available, and the V is not as quiet. ARM Systems has experimented with decoupled suspensions as a way of achieving the lowest HDD noise. They are not yet convinced that such mounting systems can consistently survive the rigors of shipping. When they devise a HDD suspension system that reduces noise further without increasing the risk of shipping damage, ARM Systems will certainly inplement it.


Both temperature and fan speeds were monitored with the Intel Active Monitor preloaded on the system. The Panaflo 92mm fan on CPU heatsink remained at a steady 1060 RPM at all loads. It is not thermally controlled. The speed of Zalman fan on the VGA cooler also remained unchanged by load. I measured the voltage across its terminals at ~6V.


* All temperatures in degrees Centigrade.

* SYS1 and SYS2 are embedded thermal sensors on the Intel motherboard.

* For your reference, the Intel P4-3.2 has a specified maximum safe external casing temperature of 70° C. ARM Systems says that throttling with this processor
never occurs below 70° C for the core temp.


* All temperatures in degrees Centigrade.

HDD1 is the bottom drive; HDD2 is the top drive. The latter's higher temps are easily explained by its position above the rising heat of HDD1 and its greater distance from the airflow of the intake fan. Seagate's maximum safe temp for these drives is a toasty 60° C, so the operating temps here are perfectly good.


As you can see, the case fans are thermally controlled, through the "Fan Control Config" in the BIOS of the Intel motherboard. This is the same feature found in an earlier Intel board that I have, which uses PWM (pulse width modulation) to control the speed. I found the feature on my board to cause fans to make so much extraneous noise that I wrote Intel's feature off as a complete failure. It's not clear to me what ARM Systems has done, but it is clear they have made it work. Perhaps it is a matter of choosing the right fans, which might explain why Steve Collins will not reveal what 120mm fan they are using.

Peak AC Power Draw

The above table shows the highest wattages seen using a Kill-a-Watt AC power meter during the activities listed. AC power draw tells us the total electrical power delivered into a PC. It is also the total heat that's being generated; it has to be dissipated effectively for the PC to work well. The higher the wattage, the more difficult it is to evacuate the heat quietly. The 236W peak was seen in PCMark04 during a combination of HDD access and complex video rendering.


A PC as loaded as this one is should perform at the top of the current pecking order. The StealthPC P4-3.2 delivers very high performance in the benchmarks, with median scores for similarly equipped systems. The latest benchmark test suites from Futuremark and Sisoftware were used.

The performance of the memory subsystems is just shy of the highest theoretical maximum achieved with this type of dual channel RAM (PC3200 CL2), and not far off from the very highest speed currently available (PC4000 CL3).

The file system benchmark is one place where performance is slightly off the mark. This is predictable, given the Seagate Barracuda SATA V drive's performance compared to the fastest offerings from other companies. However, the Barracuda V still remains quieter than the others, which explains ARM Systems' choice for the StealthPC line. Steve Collins says they are currently reviewing new SATA drive options from Hitachi/IBM, Samsung and others.


The Stealth UltraQuiet PC - P4-3.2 by ARM Systems is by far the most powerful quiet PC we've yet examined. The raw performance of the system is very high, yet the noise performance is low enough that it could easily be used as a Digital Audio Workstation (DAW) in many studios. Recording studios, both professional and amateur, often spend many thousands of dollars on sound containment cabinets specially designed to quiet their DAWs. With a system like this ARM Stealth UltraQuiet PC, perhaps such cabinets would become unnecessary.

It is also a gamer's dream machine, given the high power of the ATI-9800XT video card, the dual-channel memory, the hyperthreaded P4-3.2 processor and the RAID config of the SATA drives. From a gamer's point of view, the machine would have to be considered a sleeper, akin to a road machine moddied for maximum performance while looking most stock from the outside. (Although its weight isn't exactly inviting for gamers interested in toting their rigs to LAN parties.)

The system is certainly more power than any ordinary non-gaming PC user needs, but I have to admit that even though I pushed the system only while running benchmarks, the smooth super-quick responsiveness on on even the most balky Windows operations is kind of addictive, especially with the low noise in normal use.

SPCR old timers have a basic truism about quiet computers: You can have any two of the following -- low noise, high performance, or low price -- but not all three. (Just a variant of "You can't have your cake and eat it too".) While the Stealth UltraQuiet PC - P4-3.2 does not break our old truism, it bends it somewhat. The machine's acoustics at maximum load does not break records, but stays below ARM Systems' own self imposed standard of no more than 30 dBA at the user position. During ordinary use, it is about as quiet as any commercial production PC available.

Given the high attention to detail, out of the box plug-and-play ease, top quality construction, extended warranty and top service (by general consensus in the SPCR forums), and apparent absence of serious competition (for computers that are both quiet and powerful), the $2700 price tag represent excellent value. Your own pocketbook, DIY competence (or lack thereof), and sense of values will determine whether you agree, of course.

It's a solid, bleeding-edge PC with excellent acoustics at a fair price. Highly recommended.

Much thanks to ARM Systems for the opportunity to play with this powerful machine.

A Note to Gamers: This machine is obviously great for gaming, but ARM also offers a line of gaming rigs that look more the part, with greater emphasis on performance than on noise.

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