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Review of Silent 400w Power Supply
SnowPunk98 writes "OCModShop has done a review on a SilenX 400w 14 dBA PSU "The power supply doesn't boast any flashy designs or cool colors however that is not the purpose of this power supply. Silence is what the main goal of the unit is and there are tons of features to help achieve that.""
so here's another review of it, on a different site...
I have recently become totally fed up with the high pitched whine my main work machine made, so I decided it was about time to do something about it. I bought a Zalman silent PSU, a Zalman flower CPU cooler, two Zalman silent case fans and a Zalman heatpipe graphics card cooler. When they say silent, they aren't totally silent (except for the heatpipe graphics card cooler which has no fan), but they're pretty damned quiet.
My PC is transformed, the loud, obtrusive, high pitched whine has now been reduced to a quiet, low pitched rumbling. I struggle to hear it when I'm 10 feet away, and even when sitting by it and working it's so much quieter it's much more enjoyable to use. Music is also a much nicer experience without the fan noise. I've even found that my CPU runs cooler with the Zalman heatsink than it did with the medium priced heatsink I had in there before.
This could give you a clue. ...
14dBA is way below whisper
Well.. 0dB would be ideal, but most people cannot hear sounds that low... especially geeks with big stereo systems.
This page has an excellent table of information on various dB listings.
According to it, human breathing at 3 feet is 10dB... can you hear people breating from 3 feet away? (I can't.)
In this era of stealth advertising, one must be getting a pretty good bonus at the end of the month for getting a product on the slashdot front page.
(Yes, I'm stealing links from some of my old posts)
0 dBA may be "perfectly silent" in the sense that you can't hear it by itself, but if you put two or more 0 dBA sources together, you will hear them. The 0 dBA sources are producing sound.
Wrong. Zero dB is just an arbitrary choice and a sound at 0 dB has nonzero amplitude. In air the reference pressure is normally 20 micropascals. The previous poster is correct, the decibel scale is relative, and negative infinity dB is truly silent.
"I believe that the cult of the particular brings only death - for it bases order on likeness." St.-Exupery
For example, the Silent Boost heatsink/fan from Thermaltake is advertised as being as loud as 21 dBA. However, closer inspection will tell you that it uses an 80cm Panaflo 2450 RPM fan, and Panasonic says the fan alone (without the heatsink, which will add to the noise due to additional turbulence) is 28 dBA loud.
The same goes for all sorts of fans and PSUs advertised as being silent. Manufacturers exaggerate their claims, and the one with the lowest number typically sells the loudest product.
Typically the most irritating noises in order are
1) CPU Fan
2) PSU Fan
3) Case Fans
4) HDD
I have a Zalman pure copper Flower on my CPU with only one 12cm fan ducted near it. (No CPU fan). With my HDD decoupled it was silent (i.e. I could not hear it at 2 AM from 1 meter) during normal operation and barely audible when seek/writing.
To overclockers 28dB may seem quiet, but whispers are about 24dB. I personally find it dificult to work with someone whispering 1 meter away. About every 3 dB doubles the acoustic energy. (e.g. if one fan is 20dB, then two of the same fans would be about 23dB) I guestimate my system at about 22 dB.
And the best part is, that low frequency vibration will help the motherboard crack even faster since the Zalman coolers all cheerfully ignore the max weight limits set by motherboard companies. They have supposedly caused a few mobo deaths.
Tip- a)make sure all the standoffs are installed properly and the mobo is screwed down. b)if you move the machine, consider taking the CPU heatsink off FIRST, because if you bounce it around, the heft of the heatsink could flex the motherboard a little too much.
Please help metamoderate.
These things are neat. No fan, just a big-ass heatsink sticking out the back of your case. But remember that without the airflow from the PSU you will need a fan for your case (or a special self-cooling case).
Serve Gonk.
Zalman, Thermaltake and others neglect to specify this, which is no surprise since their claims always clash with each other and with their suppliers'.
And there's also the subjective side of things, but that's a whole other issue. Two fans with the same noise emission levels aren't necessarily as pleasant, since their spectra may be completely different. Reducing RPMs will give you less overall noise, but crappier fans will always give you irritating bearing noise, for instance, even though they may be quiet on average.
You are wrong. 0dB means a unity gain. In other words, the signal you are measuring is exactly the same intensity as the reference signal.
In audio, 0dBA (notice the A) means it's the same intensity as the smallest discernible noise to "standard" human ears. Basically it's pretty damn quiet.
You most certainly can have negative dB. It just means attenuation (ie, the signal you are measuring has less intensity than the reference signal). 0 gain (which would be truly silent) is the same as negative infinity dB.
Your stereo achieves maximum volume at OdB because at that setting there is 0dB of attentuation applied to the signal before it gets to the gain stage(s). The numbers on a stereo, or mixing board (well, the numbers below unity at least) really ought to be specified at -XdB not XdB. So when set to 15dB, your stereo is attenuating the signal by 15dB before passing it to the gain stage.
Sound Pressure Levels (SPL), on the other hand are the measured SPL compared to a reference level defined to be 0dB. 0dB is defined to the the standardized lower limit of human hearing under ideal conditions. Interestingly, for humans with no hearing loss, this lower threshold is thermally limited. In other words, if your hearing isn't damaged and there are no other sounds, you can hear the temperature of the room. At 0dB, your eardrum is deflecting by about the diameter of a Hydrogen atom. Another fun fact to know and tell: the system of small bones that convey the vibration from the ear drum to the inner ear function as a hydraulic system with a 7000:1 ratio, which is almost exactly the accoustic impedance mismatch between air and the fluid in your inner ear. For an intersting discussion of human hearing, read the first few chapters of Master Handbook of Acoustics