The Solid State PC

A silent PC is one that makes absolutely no noise, and by necessity has no moving parts (including fans). Such systems usually use very low-end hardware limited to trivial tasks such as running a cash register. The system introduced today, a Solid-State PC (SSPC) is a powerful quad-core i5 PC which runs most software faster than the majority of modern PCs, yet uses less than 25W idle.

A story familiar to many computer buyers: You go to your local technology outlet to pick up a shiny, powerful new desktop computer. While browsing available models you ask, how fast is the CPU? How much music can it store? How quickly does it start up?

You take it home, excitedly hook it up, and find that it blazing…rather loud, actually. Memory, hard drive space, processor speed — these numbers are easily found both at the store or online, and savvy shoppers know they are important. An often forgotten question, one that can be difficult to answer, is “how loud is it?” It isn’t just PCs used for home theater (HTPCs) which need to keep the noise down — many computers are just distractingly loud, annoying house guests, drowning out subtleties while playing music,  or just making it difficult to concentrate.

Some manufacturers do a good job of sound deadening. Recent models of Dell’s Optiplex, for example, use a main fan positioned cleverly in the center of the case, allowing the space inside to absorb the wind noise generated by the fan. Other manufacturers don’t do quite as well. Many designs, for example, not only use loud fans positioned against the walls of the case– they change the fan speed rapidly (and unnecessarily) as CPU usage changes. The resulting noise is difficult to ignore because it is inconsistent.

No matter how well designed a PC, silent it is not. Hard drives, component cooling, and power supplies are sources not only of unwanted sound, but the air they move contributes to dust build-up within the case. But not always:

Building Blocks

The components used to build the SSPC are listed in the table below. Components which are significant to the build are described in detail.

Type Part Details
CPU Intel Core i5-2400S (Turbo enabled) Quad core 2.5GHz (3.3 GHz turbo)
File storage Intel X25-M 80 GB capacity, 2.5″ SSD
Motherboard ASUS P8H67-M LE Intel H67 chipset (rev.3)
RAM G.SKILL ECO Series (4GB) Low-voltage memory (1.35v)
CPU cooling Thermalright HR-02 Fanless, large heatsink
Video Intel HD graphics in CPU See notes on more powerful video below
Case IN WIN IW-F430.RL Red Not ideal (see notes below)
Power supply Silverstone ST30-NF Fanless 300W


A Note on Gaming and Graphics

With an integrated Intel graphics chip, this system is not capable of playing recent graphically intense games, but it can be easily upgraded to do so. Newegg lists over 100 fanless graphics cards, many of which use modern, powerful GPUs including a nVidia GTS450 and a Radeon HD5750. While not top of the line, these are noiseless and more than capable of handling the majority of modern, graphically intense games. Please note that though fanless, these powerful graphics cards were not tested for this article and may require a better airflow than the system written about today can provide.

Cooling the CPU

The Intel Core i5-2400S is rated to use at most 65W of power. While this is less than most quad-core CPUs, it is still quite a lot of heat to dissipate when no fan is used to move air. Reduced airflow usually requires a larger heat sink to maintain temperatures, and with only convection to move air, our CPU requires large heat sink indeed.

Thermalright HR-02
The massive Thermalright HR-02 CPU heatsink [Image courtesy of NewEgg.com

The Thermalright HR-02, available at FrozenCPU.com among other vendors, is about as large as they come, and according to our friends at HardOCP, can in some cases outperform the stock Intel heatsink/fan combination – with no fan at all. It weighs almost 2 lbs (860g) and is more than six inches tall (total height 160mm), so it may not be the best choice for LAN party machines.


Notice the widely-spaced fins. This reduces the surface area of the heatsink, normally not desirable, but in the case of fanless cooling it works well to reduce air resistance. With no fan forcing air, lower resistance is more important than greater surface area.


Thermalright heatsink installed in computer
The heatsink is pictured installed below, near a set of wire cutters for size comparison.


Silent Power

The Silverstone ST30NF. [Image courtesy of NewEgg.com
Power supplies without an internal cooling fan are unusual, and units with high enough output to supply a full desktop are rare. While vendors such as Seasonic offer a small number of medium-output fanless units, I chose to go with one I’ve used in several builds in the past: Silverstone’s ST30NF.The ST30NF is not so much a power supply as it is a giant heat sink which happens to contain electronics. It weighs an incredible 6½ lbs (3KG) — more than three times the already heavy heatsink shown above, and can run reliably at temperatures so high that a “Do not touch!” warning light is installed in the back.  While it is only rated to supply a fairly average 300W, this is more than enough as we will see.



Choosing Memory



G-Skill Eco series 1.35 DDR3 memory

Modern (as of this writing) DDR3 memory is not the largest contributor to heat or power usage, but it is worth some attention.

G-Skill is one of several manufacturers which provide low-voltage DDR3 memory. This memory is available at about the same price and performs just as well as memory which requires 1.50v, the most common voltage for DDR3. A difference of 0.15v may not seem like much, but keep in mind that the power consumption (and therefore heat) of memory and many other components increases exponentially with voltage.


Notes on Cooling and Arrangement

Inside the fully assembled system

The image to the right shows inside of the fully assembled system. Look closely at the way the components are arranged.

The CPU heatsink is below, and very close to the power supply. This is less than ideal because the energy dissipated by that heatsink will move upwards (heat rises), further warming the fanless power supply. The choice of computer case for this build was predetermined, but for those building their own silent computers, I would not recommend the IN WIN case for cooling reasons, not to mention appearance.

Look instead for a case with an open fan grill on the top, which will let warm air easily escape. Look for cases which position the power supply near the bottom of the case, or at least not directly below the power supply. This will help prevent the one from heating the other. An open-air case, such as the Lian Li PC-V1000 may serve well here, even though such a design actually leads to worse cooling for computers with fans.

The layout of this case is sub-optimal, but its use proves that even in less than ideal circumstances, you do not need to choose between performance and quiet.

Necessary Moving Parts
There are no necessary moving parts, but many people use their optical drive frequently. The system in this article has no optical drive (Blu-ray, DVD-ROM, etc.), but one could be added while still reasonably labeling the system “Solid-state.” The reason is that the optical drive sits idle most of the time, making noise only when installing software or playing a movie. For the purists, an external drive can be used, as was the case when installing Windows on this computer.



Power and Temperature Measurements

Heat is of great concern for a fanless computer. Read on to find out if that concern is warranted.
Testing methodology
Component temperatures were measured using a Raytek Minitemp infrared thermometer. Ambient temperature was steady between 21.1C (70F) and 21.5C (70.7F). Load temperatures were taken after running OCCT (A program designed to maximize power consumption) for a minimum of 8 hours. Please note that internal temperatures taken with the thermometer required briefly removing the side panel of the case, which may have reduced temperature readings slightly.

In the screen captures below, please note that the system is running Windows 7, but the theme was set to “Windows Classic” in order to minimize image sizes (PNG compresses flat colored areas much better, see the article about ImageGuide).

Temperature of each CPU core at idle


At low system load, temperatures remained very cool.



Temperature of each CPU core at extreme load


At full load using OCCT, temperatures get warm.

Fortunately, even the maximum recorded temperature of 86°C (187°F) is well within safe operating temperatures according to Intel’s specification, but overclocking is probably to be avoided. Keep in mind that OCCT forces CPUs to use an unrealistically large amount of current. Duplicating this worst-case scenario with real-world software is unlikely.

Measured temperatures at load and idle
The memory and power supply get a little warm, but the memory is well within operating specifications. DDR3 can usually operate at up to 85°C (185°F) . The matter is less clear with the power supply; it’s manual, spec, and website disagree on several numbers, but the power supply is supposed to be capable of operating even when the temperature warning light is active (the warning is more to ward users away from touching it). The light did not illuminate, so I hope it is reasonable to conclude that the unit is operating safely.



Stress Testing and Power Usage

The SSPC survived two 8-hour OCCT sessions and one 24-hour session. Prime95 was run for about 1 hour, but OCCT generated a greater power load, so was used for the main stress testing. Power draw was measured using a Watt’s Up Pro power meter. Power draw of the monitor is not included.

Sipping electrons:

Full system power usage in watts

Under 25W idle for a full high-performance quad-core system is incredible. I’ve had systems which used more than that just for cooling fans.

89.2W maximum load is impressive as well, especially considering that this number will almost never be reached in the real world. Adding a more powerful video card will greatly increase both these values, but without cooling fans or spinning hard drive platters to power, current draw will still be kept to a minimum. Not shown in the graph is peak power draw: 95.3W, though this was only momentary.


Performance

Minimal performance testing was done because the components used in construction have already been thoroughly reviewed elsewhere. For example, one 80GB Intel 2nd-generation SSD [Anandtech review] will perform like any other whether in a system cooled by fans or cooled passively. The 2.5GHz Core i5 GPU [Anandtech Sandy Bridge review] theoretically will throttle at extreme temperatures, but those temperatures were not reached in testing even using software designed specifically to maximize CPU temperature.

Similarly, game performance should be the same as on any other system with the same Intel CPU-integrated GPU: Fast for an integrated graphic chip, but not fast for a gaming system. I will add fanless GPU performance metrics if a fanless GPU is made available.

While it isn’t much, I will provide the Windows Performance Index for this computer below:

Windows performance index



Conclusion

It is possible to build a fast desktop PC without the slightest compromise in noise tolerance. Temperatures are reasonable even at full load even with a sub-optimal case layout, and may improve significantly if using a more open enclosure. Power usage ranged from under 25W to under 90W

Gaming is not a strength of the system shown today, but powerful fanless video cards are available and could make fanless gaming a reality. Cooling with such a card was not tested and may require additional work.

Besides being silent, the absence of forced airflow is likely to all but eliminate dust and other debris from accumulating within the computer. The only way to truly avoid such build up is to operate within a clean room, but the SSPC should require no cleaning within its useful lifetime.

Questions? Comments? Post in the comments section below.

25 thoughts on “The Solid State PC”

  1. Great Read. I was wondering how you could get the CPU cooled effectively without a fan.

    I do wonder how long such a PC can survive some of the harsher environments such as factory floors. One of the main problems that I have seen is the fans pulling in oil or dust into the PC so while older systems such as 486s weren’t a problem, newer systems such as Pentium 4 systems were a nightmare to keep running.

  2. Even apple fan-boys can bash apple: one of the most god-awfully loud PCs I ever used was a mirror front dual G4 Mac. I never really understood quite how loud it was until I turned it off completely. Sheesh.

    As a silly aside, I have taken to collecting heat-sinks from PCs headed off to recycling. (no not multiples of the exact same thing, just one, sometimes two of each.) they can be rather interesting ‘art’ objects. Stacking them around each other they begin to look like a futuristic city. Low slung buildings of grey and black aluminum with high rises represented by the type you have pictured above. (This sort of stuff stays in my cube at work and not at home. ;)

  3. I haven’t tried to build a fanless PC in a long time, but I *have* worked hard to keep the noise to a minimum, and done a good job. Unfortunately, all of my hard efforts are ruined by the increasingly loud fan in my UPS unit. :( One day I’ll get around to trying to replace that…

    J.Ja

  4. Right now the loudest thing in my home space is my 48 port switch. May be I should question why I have a 48 port switch and not a 100 mb switch.

  5. Arg… lost my train of thought. I should question why I have a 48 port 100 mb switch and not a 8 port GB switch.

  6. @Charles

    What was the ambient temperature of the room that you were working in when taking measurements. Some of the locations that I would consider this for would have ambient temperatures easily exceed 90 F. The fanless option is definitely appealing though.

    I am investigating the cost with one of our vendors for a test system.

  7. Michael Baumli :

    @Charles

    What was the ambient temperature of the room that you were working in when taking measurements. Some of the locations that I would consider this for would have ambient temperatures easily exceed 90 F. The fanless option is definitely appealing though.

    I am investigating the cost with one of our vendors for a test system.

    The ambient temperature is mentioned in the “Power and Temperature Measurements” section.
    With an ambient temperature of 90F, the importance of an open grill above the heat sink and power supply would be a particularly good idea. Underclocking/undervolting may also be worth exploring.
    Also note that you would want a fanless power supply with a power output as close as possible to, say, 100W. Higher-rated units are fine, but in general power supplies are most efficient at about 50% load, but of course need to be powerful enough to handle worst-case power draw. There are tricks to mitigating the latter, too.

    –Charles Burns

  8. Michael Baumli :

    Great Read. I was wondering how you could get the CPU cooled effectively without a fan.

    I do wonder how long such a PC can survive some of the harsher environments such as factory floors. One of the main problems that I have seen is the fans pulling in oil or dust into the PC so while older systems such as 486s weren’t a problem, newer systems such as Pentium 4 systems were a nightmare to keep running.

    In my experience, cooling fans die before just about everything else even in office environments. I suspect a fanless unit would last much longer without maintenance in a dirty environment, though heatsinks lose their effectiveness when covered with oily goo whether or not a fan is involved.

  9. 25W idle is very good, although with a GPU it would obviously more normal like 40W. But with a (probably) lower power mainboard, like MSIs tend to be, and a more efficient PSU,like seasonic x400 you could probably still have 25W even with a discrete GPU.
    I wanted to run my system without moving parts, too,but found it slowly increses heat, over a few hours it gets too high. So now I run 2 5v fans which I cannot hear.

  10. I prefer using very large and slow moving fans. The noise can be made very subtle and we’re not trying to build something that would be used on a combat submarine.

    With the kind of load temperatures you’re getting, I’d put in a very slow 120 mm fan in the back of the case. That would significantly drop temperatures and you would have to really struggle to hear anything at 1000 RPM if it’s a good fan design. Better yet, it would be great if the fan only kicks in above 40 watt power draw.

    As for fan life, I have yet to see a slow moving (under 2000 RPM) 120 mm fan die. I’ve seen lots of 7000 RPM small fans die in servers though.

    Lastly, with a 220W 1U PSU like this http://www.zdnet.com/blog/ou/finally-a-reasonably-cheap-80-plus-power-supply/771, the PSU will not fire up the fan unless it goes above 110W. And because it’s a smaller PSU, you’ll get even lower idle power consumption.

  11. Clean room not needed if the system is completely sealed. If that were the case, the chassis itself would be the heatsink. But the CPU, chipset, memory, and anything else that gets hot should probably touch the chassis somewhere to help dissipate heat.

  12. George Ou :

    Clean room not needed if the system is completely sealed. If that were the case, the chassis itself would be the heatsink. But the CPU, chipset, memory, and anything else that gets hot should probably touch the chassis somewhere to help dissipate heat.

    ATech Fabrication makes a case like that but with the waterpipe blocks, etc., it costs more just for the case than the entire system reviewed. Still, people frequently spend more than that on even worse wastes of money, like Bose speakers, and I bet this is much higher quality.

  13. George Ou :

    I prefer using very large and slow moving fans. The noise can be made very subtle and we’re not trying to build something that would be used on a combat submarine.

    With the kind of load temperatures you’re getting, I’d put in a very slow 120 mm fan in the back of the case.

    As for fan life, I have yet to see a slow moving (under 2000 RPM) 120 mm fan die. I’ve seen lots of 7000 RPM small fans die in servers though.

    Lastly, with a 220W 1U PSU like this http://www.zdnet.com/blog/ou/finally-a-reasonably-cheap-80-plus-power-supply/771, the PSU will not fire up the fan unless it goes above 110W. And because it’s a smaller PSU, you’ll get even lower idle power consumption.

    The CPU temperatures did get a little toasty, but were still within spec, and the system did 24+8+8 hours of OCCT without a single blip. The actual usage of the particular unit reviewed will run common office apps and will probably never even utilize all four cores. Still, it can handle full bore usage.

    I was thinking of following a recommendation by Plekto on SPCR. He (she?) also introduced me to the aforementioned case.
    Using a PicoPSU, not only would nearly 100% of PSU heat output be shifted to outside of the case (a power brick), but the open area left by the mostly absent power supply would be a great spot for heat exhaust from the CPU heatsink.

  14. @Charles N. Burns

    I still think a 120 mm case fan rotating at 1000 RPM will give you a lot of cooling, produce almost no noise, and last forever given the low stresses from slow rotation. Yes I understand that you’re within spec, but it’s nice to have some cushion. Furthermore, most people will likely want a 2TB “green” silent low power hard drive for this system. It would make it a good HTPC system.

    An PicoPSU DC power supply with external brick would be very interesting. It would allow you to use a super tiny case that’s not much bigger than the motherboard, and it would likely have the highest PSU efficiency. The only issue is that bricks are annoying and a bad form factor. This is why the new Apple TV incorporates the AC PSU inside the case.

    This tiny 55W open frame AC PSU is pretty sweet, but it’s a bit underpowered. I’m not sure if they make a 100W open frame PSU. The other option is to disable the dynamic overclocking in the CPU and GPU to keep the DC power under 55W. You might have to limit the maximum clock speed and undervolt the CPU to achieve this.

    The easiest thing to do is probably just stick with their 250W 1U PSU. It has a fan but it only comes on when loads exceed 110 watts. That means for the solid state system you built, the fan will never come on even with GPU loads and even if you added a few hard drives. But it’s nice to know that if it’s needed, it will turn on.

  15. @George Ou
    I agree with you on fans. I’ve used Skythe Slipstreams (500, 800 and 1200 RPM models) and they’re all fairly silent. If I replaced the fan on the GTX260, I suspect it’d be inaudible even if I killed all electronics, including the AC/heat and Refrigerator.

    Those slipstreams are nice and relatively cheap compared to most “silent” fans.

  16. {Pink Floyd style music in the background…} Hello…. Is there anybody out there… just WRITE if you still POST here… does anybody care?

    Really, are you guys still keeping this site, or have you gone on to greener pastures?

    This was the last posted blog entry, which is approaching 2 months.

  17. @DEK46656

    I can’t speak for George, but I’ve been running full steam ahead with a number of other projects, and this one is (unfortunately) last in priority. I’ve got a number of article ideas, but no time to post them. :(

    J.Ja

  18. I am wondering if a pico psu would make any difference to the energy consumption? Should be even more efficient (and one less source of heat inside the case).

  19. @Mike
    I bet it would make a significant difference in total energy consumption because full-sized power supplies tend to operate at low efficiency when supplying a small fraction of their total rated output. Additionally, the power supply I used isn’t even 80+ certified. A more efficient, modern unit would save 10%-20% power just based on quality of electronics.

  20. Look at the TrimSlice by Compulab – 5W, Dual CPU – Tegra2 – and wait until May 2012 and get a Tegra3 (5 CPU) super-computer running at 2.5W…or look at the “Cotton Candy” cloud/hdmi/usb machine…

  21. It is imperative that you typically apply the top CPU coolers one can get to avoid your CPU from overheating. With computer games on the rise and HD and 3D games and movies now being experienced on your PC, almost all of these media types will often put some demand on your PC’s hardware and cause temperatures to go up in your CPU, RAM and video card.

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