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