Technically, this should be a very simple product – move a slider, and the resistance of a switch changes, and excess voltage goes away as heat – but that would mean dissipating up to 90 watts of heat if the fans are moving at minimum speed, which is clearly not happening. As luck would have it, the controller was plugged into five bright-green LED fans, which flicker noticeably when the fan speed is slowed. What does this mean? Pulse-width modulation. The potentiometers carry only a signalling current, and the system uses the signal to determine the duty cycle of a fast solid-state switch. Unfortunately, fast does not mean instantaneous, and changing electrical fields create magnetic ones which can induce current in other conductors. This explains the only observation that separates the Sentry Mesh from perfection, namely that the pulse-width modulation is slow enough to be audible in the form of noise magnetically induced in the front panel audio jacks – neither the Sentry’s cabling, nor most fans use shielded cable, and neither is my case’s audio cabling – yours is probably unshielded, too. While the flickering may be noticeable, it was unobtrusive, and also provided adequate dimming of the LEDs in the fan to indicate speed – useful in that the Sentry Mesh lacks any kind of feedback mechanism, and many enthusiast cases have some kind of cover over the drive bays. If you find the thought of flicker unpleasant, I recommend using non illuminated fans and using some kind of cold-cathode or LED lighting that operates independently of the Sentry Mesh’s control (or alternately, just not using an illuminated case at all). The only remaining issue is that of audio quality on the front headers, and perhaps interference with the USB signalling that passes just centimeters away from the headphone plugs on most systems. While I have no effective way of measuring this interference short of an oscilloscope, and my devices and transfer speed seemed to be operating within the bounds of normal, on an already marginal system this could pose issues. On the other hand, when the throttle is wide open, the Sentry delivers 12v DC with a 100% duty cycle, and any audio issues disappeared when all fans were operating at maximum speed. Recall that it is changing electrical fields that create magnetic fields, and this should make more sense – in this mode of operation, the power only goes on or off when the entire computer does so simultaneously.
|I’d say there’s room for a 2.5″ bracket there.|
I understand that some people want a fan controller they can order a pizza from, but most computers will be quite adequate to handle this task without doing the deed on a front-mounted touchscreen. NZXT’s Sentry Mesh is entirely adequate for running a lot of fans, and still being able to dial them down to preserve some semblance of quiet when necessary – or crank them up to dump the heat of a powerful computer operating under heavy loads. The simplicity of operation is a refreshing change compared to the heavily automated systems that dominate this market segment today, and I believe a great many of our readers will appreciate this simplicity as well. I also expect that using rear-panel audio plugs should be a simple enough solution for those who dislike the noise on the front-panel audio, and a great many multimedia speakers offer a 1/8″ headphone jack to bypass the front panels entirely. Perhaps on the next revision, NZXT will be able to increase the pulse width to an inaudible frequency – or perhaps they chose this one deliberately to avoid potential noise from the USB connections. They might also consider adding a mounting point for a 2.5″ SSD or two, as that seems to be the trendy thing to do lately in this sort of shallow bay device. In spite of this one niggling issue and the potential for improvement elsewhere, the product is unarguably excellent. Its simplicity of operation and broad compatibility with enthusiast cases will undoubtedly make it a popular choice among those who worry about such factors as the relationship between computer noise and cooling.
|The Sentry Mesh above a DVD burner||The Sentry Mesh’s backside, showing how short its electronics are|
In practice, the flaws I point out in the Sentry Mesh are either more in the vein of feature suggestions for next year’s model (SSD mounting brackets) or universal problems with PWM anything (audio noise induction). At a street price of $26, the latest Sentry is a remarkably good deal compared to $60+ touchscreen devices, and it gets the job done. It’s also dirt simple to adjust, and while this will involve taking your hand off the keyboard or mouse, it doesn’t necessarily require taking your eyes off the monitor, and if you’re deft, you can max out all five sliders with one swipe and one hand. Around here, solid, inexpensive hardware is generally very well received, and this is no exception – while it lacks bonus features found on a few other units, these are bonus features, and can’t be expected in every device brought to market. And on top of that solidity, we must add some style – the Mesh is channeling mixing boards and high-end equalizers with those parallel sliders, and because the only LED it sports is white, it’s easy to make it fit a great many themes. As it stands, it seems remiss of me to not offer some form of recognition for NZXT’s well executed engineering efforts.