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March 17, 2006 by Mike Chin
Concern about computer noise was expressed only by a tiny segment of power users back in 2001 when SPCR was first conceived. These were people who worked around computers constantly and ? whether by natural disposition and sensitivity or by over-exposure ? were bothered by the noise of screaming hard drives and fans. There may have been others who didn't like computer noise either, people working in offices, or innocent bystanders sharing living space with die-hard gamers and their noisy PCs, but they were rarely vocal. Even when they were, no one seemed to hear them.
Today, in March 2006, SPCR is nearly four years old and gets some half million unique visitors every month. An interesting aspect of our traffic is that the geographic distribution of our visitors perfectly reflects the online populations in the world. We interpret this to mean that the interest in quiet computers crosses all boundaries. SPCR is no longer the only web site to pay attention to acoustics in computing gear. Many other hardware review web sites at least mention noise in some of their reviews, and some take it quite seriously. Still, SPCR is almost alone in our systematic and holistic approach to assessing PC noise, not only measuring but analyzing closely with our own ears and recording the sounds for readers to hear for themselves.
We still listen.
NOISE AND HEAT
Very early in our history, SPCR made the undeniable connection between PC noise and thermals. Expressed simply, it goes like this:
- Much of the noise produced by a computer comes from the fans.
- The fans are necessary to cool hot components and to evacuate the hot air from the computer.
- The hotter the components, the faster and louder the cooling fans must run.
- An obvious way to reduce noise is to slow down the fans, but in order to do so safely, the components must generate less heat.
- The less heat there is in the computer, the easier it is to make it run silently.
These simple observations form the basis of much of the content of SPCR, from the reviews to the advice routinely dished out in the forums. There are many fine nuances and extensions of the silencing mantras, but it's not astrophysics.
HEAT & POWER EFFICIENCY
When we examine thermals and power, things get a little more complex. In general, the amount of power consumed by an electronic device is equal to the heat it generates. Hence, the power consumption of a PC measured at the AC socket tells us how much heat is in the box. This is complicated by the fact that whenever electrical energy is transmitted or converted (from AC to DC), losses occur. Inside the PC, losses occur when:
- The AC is converted into DC within the power supply. (The power supply provides three DC voltages: +12V, +5V and +3.3V.)
- The 12VDC is converted by the voltage regulation module on the motherboard into yet lower voltages for the CPU (typically <1.5VDC).
The most efficient power supplies (PSU) for PCs have an AC/DC conversion efficiency of >80%. The most efficient VRMs on desktop motherboards may approach 85%. This means that from the AC to the CPU, the best power efficiency is no better than about 70%. Both the PSU and the VRM are much less efficient at higher and lower power levels ? including idle, which is where most computers operate 95% of the time. So perhaps a realistic AC-to-CPU energy efficiency figure is about 60%. This means, for example, that a CPU requiring 30W at idle actually draws 50W at the AC socket. The remaining 20W is lost as heat inside the PSU and on the motherboard VRMs. Of course, the 30W that does get delivered to the CPU also ends up as heat, which has to be dissipated with the help of a heatsink and fan.
In recent years, there has been increased attention on improving the efficiency of the power supply. SPCR played a small part; we were the first PC hardware site to analyze and report PSU efficiency, initially as an adjunct to acoustics, but increasingly as an item of interest all on its own. We still remain one of the few hardware sites that analyzes PSUs with any seriousness. The 80 Plus program to certify and encourage the use of high efficiency PSUs by system integrators, and the rising standards for efficiency in the widely accepted Intel-driven ATX12V (and other form factor) power supply specification have helped to increase awareness of the benefits of higher power conversion efficiency. It would seem that power supply efficiency remained virtually unchanged for the first couple decades of the PC's history, but in the past couple of years, the average efficiency of higher priced models has improved dramatically.
Noise remains tied to heat.
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