Sonata's recipe for silence
Around back, the Sonata's real magic is revealed.

Nice rear

Here you can see the enclosure's two fan openings, one in the power supply, and the big momma below it for a massive 120mm low-RPM fan. This big beast pushes 79.06 CFM at a peak of only 2000 RPMs. Antec says the fan puts out 29 dB of noise.

My, that's a big fan

Antec's TruePower 380W power supply garnered an Editor's Choice award here at TR a while back. The TruePower 380S unit in the Sonata is a special, single-fan version of the TruePower 380W that's not sold separately. Both the power supply fan and Big Bertha are speed-controlled by the TruePower 380S, which has an internal temperature sensor. The TruePower directs the fans to speed up or slow down depending on internal case temperatures.

This arrangement makes for a very quiet case, especially when the system isn't under extreme loads. I found the TruePower 380S did a good job of knowing when to turn up fan speeds in response to rising case temps. The numbers produced by the sensors on my motherboard via Motherboard Monitor tended to correspond pretty well to the decisions the TruePower 380S makes about raising or lowering fan speeds. And the numbers were quite decent. After an overnight Folding session inside the relatively warm Damage Labs underground complex, my CPU temp rarely cracked about 136 degrees Fahrenheit. (That's about 57 degrees Celsius, for you freaks and weirdos.)

My system, for the record, has an Asus SK8N motherboard, Opteron 146 processor, Radeon 9700 Pro graphics, 2GB of RAM, Sony DVD RW drive, and a Western Digital JB-series hard drive. Its thermal load should be similar to most mid-to-high-end setups these days.

How quiet is the Sonata? Well, we couldn't simply place the Sonata in quiet room, stand a few feet away, and measure it with our sound level meter, because the Sonata doesn't register. Too quiet. So I held the meter (Extech model 407727) up close to the case and measured it. What's more, I measured the sound level and idle and under a full CPU/GPU load (running Folding@Home and the ATI "Chimp" demo). To provide some context, I also measured a few systems in other cases, including an Antec SX-830 (with an Athlon XP 2100+), a Shuttle XPC SN41G2 (with an Athlon XP 2800+), and a CoolerMaster WaveMaster (very similar to my system, but with an Athlon 64 FX-51). All of the systems are fairly typical configurations, and I avoided extra noise from things like busy hard drives or screaming GeForce FX Dustbusters. Here are the results.

I didn't take "load" readings on the SX-830 because practically nothing in the system adjusts fan speeds under load, anyhow. The thing is just that loud all the time. The WaveMaster system doesn't have an OS installed yet, unfortunately, so I wasn't able to take readings under load for it, either. Nevertheless, these numbers should give you a decent idea how the Sonata compares to some other common cases.

During the tests, I couldn't get all the fans in the Sonata to remain at the fastest speeds. The system just doesn't get hot enough to trigger a steady run at the highest speed setting, even under heavy load for an extended period. However, I did manage to measure the Sonata during some short bursts at top speed. From the front, it hit a peak of 54.9 dB, and around back, the peak was 62.5 dB. If you happen to load up the Sonata with something really hot, like dual Opterons or an Intel Prescott, the system running full tilt may get nearly as loud as your average mid-sized ATX enclosure.

What you should take from these numbers is that the Sonata barely whispers during normal use, and isn't terribly noisy when the system is really churning on something. Also, importantly, the Sonata projects much less sound out of the front than out of the back. Given typical placement in a typical room, where one's computer desk backs up to a wall, that matters. Subjectively, the Sonata more than makes good on these numbers. It is easily the quietest ATX or small-form-factor case I've ever used.

However, the Sonata isn't quiet perfection. When I popped a graphics card with a noisy fan (bad bearing, I think) into my system, the Sonata's quiet fans and clean design didn't seem to help mask the noise from that fan much at all. And when my DVD RW drive spins up, the Sonata can't do much to dampen its whine. You will need to choose your other system components wisely in order to build a silent PC.

Also, the TruePower has a limited number of fan speeds, and it's apparently not very sophisticated about controlling the transitions between them. Sometimes, when I'm working at the computer, the ambient temps and the load from my computer will conspire to create a fairly stable temperature inside the Sonata that's right on the threshold between one fan speed and the next. Then, Big Bertha back there starts transitioning up and down between two fan speeds. Quickly. Although the Sonata is much, much quieter than my last computer or any typical ATX enclosure, these transitions can be nearly as annoying as a loud computer—more so, perhaps, for some folks, because of the changes in pitch.

This is, in my book, the Sonata's greatest weakness as a piece of equipment designed to make one's workspace a more enjoyable place to be. It's no deal killer—not by a long shot, because the Sonata's a huge step in the right direction, but there is room for improvement in this area. Ideally, the Sonata would have infinitely variable fan speeds and some reasonably smart control logic to minimize the distractions created by fan speed changes. However, I'd settle, for starters, for a measure of user control, ideally through software-selectable temperature/fan-speed thresholds.