Digital Storm's Core i5 System Reviewed

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Decibel Level, Thermal Testing

Sounding Off:
When the Digital Storm system arrived, we initially installed it in the test lab, within about 10 feet of my own desk. By the third day of testing it, I'd moved the system into a separate room altogether. Not only was the DS i5-750 system intolerably loud, it was loud at a particular range of frequencies that, while not immediately nerve-wracking, turned out to be the aural equivalent of Chinese water torture. The first two suspects were the power supply and case. The former was seemingly confirmed as the cause when we spoke to Digital Storm themselves—they "highly recommend" a much quieter and more expensive PSU from Corsair. When we went scrounging for information on the Cheiftech's decibel rating, what little data that was available pointed towards a dBA level between 42-47.

Initially, we took Digital Storm's word that the noise levels were caused by the power supply, but this turned out to be somewhat inaccurate. Near the end of my performance tests, we swapped out the Chaintech for a 750W PC Power & Cooling Silencer. This did help quiet the system—but only a little. Our second suspect—the HAF932—wasn't the direct culprit either. There's a short explanation and a long explanation for the system's dB output, you can choose which you prefer.

The Short Explanation:
The i5-750's 66dB boot volume and 54dB idle volume is not caused by any single component, but by several. The power supply, dual EVGA GTX 275 cards, and the company's choice of case and radiator fans all directly and materially contribute to the problem. The design of the HAF932 exacerbates the situation. Because the case is basically a giant sieve, pushing air through it creates more wind noise than is typical. Place your hand on the front of the case (which is nothing more than a giant grille, from top to bottom), and you can feel a distinct stream of air being pulled inside.

As constructed and shipped, the system is at least acoustically disagreeable; system noise can be substantially reduced with virtually no impact on the system's operating temperature. Given this, we strongly suggest Digital Storm modify the cooling options available from its website. Despite the fact that DS identifies our system as having shipped with "stock chassis fans," none of the fans in question are stock models from Cooler Master or Asetek—offering the option to install different, quieter fans should be no problem.

The Long Explanation:
We'll start with the Digital Storm i5-750's dB ratings as measured at a distance of one foot at the front, side, and back. Unlike a standard benchmark or temperature reading, decibel ratings are logarithmic. 63dB is twice as loud as 60dB, 66dB is four times as loud as 60dB, etc. A 40dB sound is 100x louder than a 20dB sound. Remember, a system is only as quiet as its loudest measured dB level. If the back of the case is kicking out 66dB, it doesn't really matter if the front is somehow just 20dB. The dB meter we used can only detect sounds that are 50dB and upwards.

The system's high boot volume is driven exclusively from the back of the case, which is much louder than the side. If you think about it, this makes sense. The side of the case has a single, 240mm low-speed exhaust fan, while the rear of the case is the exhaust point for the CPU radiator fans, two GTX 275s, and the power supply. Once the system boots and the GPU fans drop back to 40 percent, the system's sound is more evenly distributed.

The rear of the case was the obvious place to focus—and since we didn't want to change the review system's hardware configuration, that left the CPU radiator fans and front case fan. That, folks, is where things get really interesting.

Mi Casa, Akasa:
As we noted earlier in the review, the DS i5-750 uses two fans, one on either side of the radiator. This seemed a bit odd, given that one purpose of watercooling is to use less fans, but we assumed the company had outfitted the radiator with two low-speed, ultra-quiet fans, and was using two of them rather than a single, higher-speed unit. This turned out to be decidedly untrue. The two fans attached to the radiator are both manufactured by Akasa, model number: DFB122512L. There's a third, identical fan mounted in the front of the case.

It's not entirely clear what the specs on these fans actually are. It's not listed as a product on the manufacturer's website. The image is of a visually identical blue LED model, but the specs don't appear to match our baby (which could also be one of these beasts). The DFB122512L is listed by part-number over here, where it's specced as pushing 35.12 CFM and running at 25.24dB. For lack of a better reference, we're assuming the CPC-given specs are accurate.

Watch what happens to the i5-750's dB level when we disconnect the entirely spurious front fan and swap out the radiator fans for a
single Thermaltake TT-1225. (For the record, this one also glows blue, and matches the Digital Storm color theme nicely.) In the configuration measured below, the TT-1225 is mounted closer to the CPU and is pushing air over the radiator and out the back, rather than pulling it.

A measurement of "<50" means the decibel level was below the detectable threshold of the meter. Replacing the two radiator fans with a single, different fan cut the dB level at boot significantly. Once in idle mode, we couldn't pick up a reading at one foot from any of our previous test distances. Even if we assume the system's dB level is hovering right below the limit of the meter, at 49dB, we've still cut the system's sound by nearly four times. One thing to note is that the dB drop at the front of the system was caused by the disconnection of the front case fan, rather than by the radiator configuration changes. The reverse is also applicable—the front fan's status didn't impact our dB measurements at the back of the case.

The logical question at this point is to what degree these changes impact the temperature of the processor, as discussed on the next page.

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