March 17, 2004 by Mike Chin
Product | StealthPC Foundation Kits |
Manufacturer/Vendor | ARM Systems |
The ARM Systems StealthPC P4-3.2 Powerhouse was reviewed here January, to much kudos from SPCR enthusiasts. There was a great deal of interest expressed in the case ARM Systems uses for their PCs. In response to the expressed interest, Roy Manalastas and Steve Collins of ARM Systems have begun offering StealthPC Foundation Kits for Do-It-Yourselfers. The Foundation kits consist of their noise-optimized mid-tower case with top quality damping fully applied, an ultra-silent modified Zalman power supply, and various noise and vibration reduction devices.
StealthPC Foundation Base Kit Contents
ARM Systems are flexible about the exact configuration of the kit, and can adjust contents and price based on customer requirements. Their PDF promo / price sheet provides information on three kit options. Please note that all prices quoted here are valid at time of posting but subject to change without notice.
1) The base US$249 CA-ST-KIT-4252-1 kit consists of the following:
- 1 – Evercase 4252 mid-tower case w/120mm rear exhaust vent and one detachable dual-HDD cage equipped with EAR hard drive grommets and matching screws
- 1 – RamAIR Cold Air Induction CPU Duct System
- 2 – Quiet 120mm ARM System brand fans, premounted on exhaust and intake vents with EAR grommeted screws
- AcoustiPack damping materials treatment of all interior case panels
- 1 – Zalman ZM300B power supply, ATX12V v1.3 compliant with ultra quiet Panaflo fan modification.
- 2 – Zalman Fanmate1 fan voltage controller
2) The US$299 CA-ST-KIT-4252-2 kit provides an upgrade to the higher power Zalman ZM400B PSU, also Panaflo-modded.
3) Their $499 CA-ST-KIT-865-28 addition is sold only with either of the above kits, and turns them into almost complete prebuilt systems. Only memory, VGA card, drives and preinstalled OS are missing:
- Intel D865GBFL or D865PERLX motherboard (Specify at time of order)
- Intel P4-2.8Ghz 800 FSB 512K Cache Processor, installed
- SLK947U (Thermalright) CPU Cooler w/ 92MM Quiet fan / Fanmate, installed on motherboard w/ Arctic Silver 5 High Performance Thermal Compound
- Fan adjusted to optimal setting for cooling and noise reduction.
- Motherboard is installed in case / tested and BIOS updated prior to shipping.
- Also included in kit: ATA Cable, HD Cable, (2) SATA HD Cable, cable ties.
- Depot Parts warranty – Motherboard and CPU (3 years)**
NEW CA-ST-KIT-4252-2 KIT
Recently, ARM Systems shipped over a review sample of a new prototype version of the CA-ST-KIT-4252-2 kit with the 400W PSU. This kit will be available very shortly.
By now, SPCR readers are familiar with the Evercase 4252 that ARM Systems uses in the StealthPC line. There are numerous photos in the previous StealthPC P4-3.2 Powerhouse review. Here is a look at this new prototype:
Perhaps the difference is not immediately apparent, because it is difficult to capture details in the black. Here are a couple of looks at the interior. Note power cord and other goodies in the plastic bag.
By now, you will have noticed that the Zalman PSU looks a bit too long. A closer look:
Yes, there is an extension to the back of the PSU, a little black box that looks completely closed… except for this vent at the top of the case. The green arrow is there just to make sure you see it.
The grid of holes on the top do not function like a conventional “blowhole”; it is an intake vent. The little box on the PSU is actually a duct which forces the PSU fan to draw in air only through the top vent holes.
ARM Systems have created the first commercial implementation of a case cooling / quieting feature I’ve been espousing in SPCR for over a year. However, their version does not rob the case of any external optical drive bays.* It is…
A FRESH AIR INTAKE DUCT FOR THE PSU!
The duct is a small 4-sided box made of a high temperature, flameproof, no-melt mylar. It feels like very smooth heavy card stock business cards, I mean. The two open sides face the top, where the vent holes are, and the intake side of the PSU. The mylar duct is attached to the PSU and the inside of the top case panel with what appears to be black electrical tape.
The holes on top have obviously been done manually, judging by the uneven pattern. Roy Manalastas of ARM says not to be too concerned about how this prototype looks. They have arranged for Evercase to custom manufacture ventilated versions of this top panel. ARM Systems have exclusive rights to Evercase 4252 cases outfitted with this top panel vent.
All StealthPCs and Foundation Kits with 400W PSUs (or larger) will be equipped with the PSU fresh air duct. There is also consideration of offering just the top panel as a retrofit mod for all the thousands of customers who have purchased ARM System PCs built in this chassis. The top panel is easily removed by accessing two locking screws hidden under the front bezel. This would allow older systems to be cooler, quieter, and/or allow better upgradeability with hotter components.
The benefits of the PSU fresh air duct are simple:
1) The PSU always gets the benefit of cooler ambient air rather than the preheated air from within the case, and from the CPU. The temperature advantage can be over 20°C.
Much of the hot air rises and tends to pool at the top of the case where it gets sucked into the PSU. Actually, this is a defined design function of the PSU within the ATX specification. However, the ATX specification was created nearly a decade ago when systems barely created 100W of heat in a case. Today, the CPU alone can create this much heat! Using the PSU as an exhaust fan has the great detriment of channeling a huge amount of heat through an electronic device that already runs hot.
2) With cooler air, the thermally controlled PSU fan tends to run at minimum speed and rarely ramps up. Because the PSU sees so much less heat, it runs cooler, and the fan only has to evacuate only the heat that is generated by the PSU. This is typically 25~35% of the total AC power drawn by the system. This means that the internal thermistor which controls the fan speed in a modern PSU rarely sees temperatures high enough to increase the voltage to the fan. Normally, if the PSU shares the job of evacuating the hot case air with a case fan on the back panel, it is dealing with at least ~50% of the total heat in the system.
3) Acoustically, the end results are lower PSU noise, and less variability in PSU noise. The latter aspect is as important as the former: Even at low volume, small changes in noise are easily heard as annoyances, especially if they are frequent. In my own DIY implementations of PSU fresh air intake venting, I’ve been able to run up to a 170W (max total heat) system with a Seasonic or Zalman 400W PSU with virtually no speed up of the PSU fan in normal use.
There is only one or two potential downside:
The task of evacuating the hot air from the case falls entirely to the back panel case fan. Because the PSU fan is no longer pulling the hot air out at the top, the back case fan now must evacuate 65~75% of the total heat in the system. In the ARM Systems case, the 120mm fan should be able to handle this fine on its own, at least up to hottest current desktop CPUs (~100W).
With really hot components and/or inadequate case airflow, the PSU fan may still end up running faster. This is because the CPU is located just directly below the PSU, and only a thin steel wall insulates the PSU from the CPU heat. Still, even if it did occur, it would occur less with the duct.
(* The first appearance of the PSU fresh air duct idea was in Leo Quan‘s Dual MP System article. I’d suggested it might cool his beast more quietly. The most complete documentation of a PSU duct implementation was by Lilla in the SPCR Forum thread Building a PSU intake duct/vent: In this thread is a link to a personal website by Lilla featuring details of a system that incorporates a very nicely made DIY PSU duct.)
TRIAL APPLICATION
To find out how well this prototype StealthPC Foundation kit works, it would have been great to compare it with one system against another identical one without the PSU intake duct. Unfortunately, a second case was not available to me at this time.
An Athlon 64 3200+ System
I assembled a system with this prototype StealthPC Foundation kit:
- AOpen AK89 Max (nVidia3 Athlon 64 board)
- AMD Athlon 64 3200+ (spec’d at 89W)
- Zalman ZM7000A-AlCu heatsink w/ fanmate1 set to 5V
- ATI 9800 Pro VGA with Arctic Cooling VGA Silencer (fan set to low)
- Crucial PC3200 memory, 512MB
- Samsung SP0802N hard drive, mounted with the supplied EAR soft grommets
- Samsung SM-252B CD-RW Drive
- 120mm exhaust & intake fans (as supplied in the kit) set to 5V
The so-called RamAIR Cold Air Induction CPU Duct System i.e., the side CPU intake duct is adjustable for height (or depth) and can also be moved from side to side. With this motherboard, the duct ended up slightly too high and too far back. It can be moved easily enough, and I don’t doubt that better positioning would improve CPU cooling (and maybe even case temps) by a few degrees. However, the duct stayed where it was. The inflow of air through the outside opening of the duct could easily be felt; I am sure it helps.
The maximum AC power draw of the system was with CPUBurn stress testing: 165W. That number represents the total heat in the system.
Silent Nutter’s Rig
This is 26W higher than my main rig, a P4 system that hits max AC power of 139W. This system differs from the above in the following ways:
- Intel P4-2.53
- Zalman ZM7000-cu @ 4.5V
- AOpen AX4GE Max motherboard
- Matrox G400 Max VGA cooled by Panaflo 80L at 6V with exhaust port created by removal of PCI slot covers
- Seagate Barracuda IV 40G x 2 hard drives in DIY elastic suspension
- Panaflo 80L fan at 6V for intake & HDD cooling
- Selective sound damping on interior case panels
- Zalman ZM300A PSU modified with Panaflo 80L fan; entire PSU located on top panel, outside case.
A unique aspect of this system is that the PSU is running OUTSIDE the case, and thus completely unaffected by any of the heat in the case. Another benefit of this arrangement is that the case airflow is greatly improved by the absence of the PSU in the top corner. Instead of a 30-40W source of heat, there is a gaping hole, an exhaust vent of about 5″ x 3″ through which rising hot air evacuates from the case. There is no back case fan; the 80mm hole for it is left empty. Only convection is used for heat evacuation from the case.
In a nutshell, this rig is…
- Totally tweaked over the course of nearly two years with the quietest components I have found or modified.
- Utterly impractical and unsellable as a commercial system.
To compare this customized and hacked Silent Nutter’s Rig against a hotter system slapped together in a morning in ARM Systems’ eminently practical Foundation Kit is patently unfair. But that’ precisely what I am going to do.
Both systems were placed on 1.5″ thick pieces of closed cell foam for acoustic insulation from the hardwood floor under the desk in my home office, which measures just 10′ x 10′ (with a 8′ ceiling). The middle of the floor is carpeted. The sound level meter was placed 1 meter from the front or back panel each computer on a cushioned chair with the microphone at the same height as the top of the case. Here are a range of relevant measurements after half an hour of CPUBurn on each PC. (In both cases, temperatures stabilized and remained unchaged after 15~20 minutes.)
CPUBurn: 30 minutes | StealthPC Foundation kit Athlon 64 | Silent Nutter’s Rig |
Noise Front | 26 dBA/1m | 21 dBA/1m |
Noise Back | 29 dBA/1m | 24 dBA/1m |
CPU* | 56°C | 59°C |
Case* | 44°C | 45°C |
PSU Temp** | 37°C | 32°C |
AC Power | 165W | 139W |
**Thermal probe within 1cm of PSU exhaust, positioned for highest reading.
Room Ambient: 25°C and 17 dBA
One very important thing to note with the above table is that there is no minimum and maximum for noise levels: Both system stay at the same noise level whether at 100% load with CPUBurn or idling with AC power at 70% of the max. This is because the case and CPU fans were at fixed low speeds, and the thermally controlled PSU fan never ramped up in speed in either system.
When you consider that my Silent Nutter’s Rig PSU had the cooling benefit of being entirely out of the hot case and handling 26W less heat, you can see that the ARM Systems PSU fresh air duct system really does work. The exhaust air temperature from the Foundation kit system was substantially hotter, but still cool enough to keep the PSU thermistor from ramping up its fan.
It is easier to describe the acoustic signature of the Foundation kit system more by what it doesn’t do than by what it does:
- No case vibrations or resonances
- No whining or high frequency noises of any kind
- No big whooshing airflow turbulence noise
- No intermittent louder/softer noises
- A small amount of HDD noise during seek, very muted
- A bit of bearing chatter or whirring, especially late at night when the ambient noise is very low
CONCLUSIONS
Is the 5 dBA difference between the two systems audible? Yes. In the daytime ambient of my home office (low-to-mid 20s dBA), the Nutter’s Rig is usually not audible where the nutter usually sits. The Athlon 64 system assembled in the StealthPC Foundation kit is a bit over the cusp of audibility. Much of this can be credited to the 120mm fans. The fans are the one area where some improvement can be made… but I am not sure that I have heard any that are significantly quieter. Quiet 120mm fans are tough to come by. It has to do with the sheer moving mass of the blades, the larger size of the bearing, the higher volume of air it moves. Maybe >$20 Papst fans could give better performance but at this low speed? I am not sure. I doubt any system with 120mm fans could best my Nutter’s Rig with its Panaflo 80Ls hand-picked for lowest noise at low voltage. (I know that comment is probably going to be seen as a gauntlet by many dozens of SPCR regulars…)
Is 26 dBA at 1 meter loud? Heck no, it is very quiet. For anyone who is used to “normal computers” it is probably going to be heard as silent for a week or longer. If your ambient noise is higher than mine, then you may perceive it as silent forever. But your background noise is similar, then you will become acclimatized to the new lower noise level and hear these 120mm fans. Regardless, it is a very quiet level, especially for a system as powerful as this one.
Can
a system quieter than 26 dBA/1m be built using the ARM Systems StealthPC Foundation kit? Yes. The noise floor is set by the Panaflo-modded fresh-air ducted Zalman ZM400B power supply, which is at 20~21 dBA. The trick is to find case fans that are substantially quieter and still move enough air. With cooler components than what I chose here, it should be feasible to use even 80mm fans at low voltage for a noise level similar to my Nutter’s Rig. But chances are, you’ll probably be more interested getting the StealthPC Foundation kit with an eye to a quiet high performance machine. (ARM Systems says they’ve assembled and shipped some burning-edge P4-3.4EE systems with this new PSU duct system that has the same acoustic signature as the significantly cooler P4-3.2 system I tested earlier.)
Unless you go crazy with noisy, hot components, it’s hard not to make a quiet system with ARM Systems’ StealthPC Foundation kit. You get:
- One of the best ventilated mid-tower cases with the best acoustic bezel design
- PSU fresh air duct unavailable elsewhere unless you DIY
- Great acoustic damping materials preapplied in the case (a lot of work!)
- An excellent 400W PSU with high 75% efficiency and ATX12V 1.3 compliance (high 12V line current) modded for extremely low noise, warrantied by ARM Systems
- Virtually all the parts associated with the case that are needed for a high quality, high performance quiet rig.
It looks like very good value, and hard to beat for sheer thermal / acoustic performance. Especially if you value your time at all, because ARM Systems have done the research and testing to assemble this quiet package of goodies. That PSU fresh air duct looks to me like the sweet topping on the cake. (Of course, you’ll say I am biased because they liked my idea and ran with it… Nah: I am always biased for good simple ideas that work, no matter who comes up with them.)
Much thanks to ARM Systems for the opportunity to examine this prototype package.
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