The WD Purple is a surveillance drive with low power consumption and a design that's optimized for 24x7 operation. There is actually little beyond marketing that separates the Purple from the Red and Green drives. They all share almost identical hardware. The thing that does differentiate the Purple drives is their firmware which supports AllFrame, a surveillance specific feature. Allframe handles the cache in a way that is optimized for video streams. The AllFrame technology however is only enabled when used in conjunction with a supported host controller, most of which are only found in dedicated NVR (Network Video Recording) devices. As a result there is no benefit in using this drive in a HTPC to record video streams, because the surveillance specific functions won't be enabled. In terms of effective speed the Purple lags the new Red and Green drives by around 26%. ^{[Oct '14 HDrivePro]}

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