The Black Art of Dual PSUs in Your Enthusiast PC

Putting two powers supplies in your computer has been a recurring subject in our forums for years. While the physical process of making that happen is not exactly rocket science, it still can be daunting for some users. Today we show you a few products that make it easy for anyone to double up on the power should your wattage needs increase.


FSP Booster X5 450W Overview

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As we see here, the FSP Booster X5 450W comes with what we would consider the usual assortment of items that come with a modular power supply including a user manual, modular cables, an AC cable, mounting screws, and a mounting bracket for the AC cable to pass through an unused expansion slot on your case. The manual that comes with the unit really only serves to provide users with the installation instructions, and buried on the FSP website, but nowhere else with the unit, we find that the product has a 3 year warranty. Lastly, the product makes reference to "Over Clock Running to 500W Peak," which is not exactly true as the power supply is not "overclockable." Rather, the unit simply has a peak output rating of 500W for a short undetermined time unlike it’s claimed 450W rating which is supposed to be continuous.

FSP Booster X5 450W Function

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As we see in the pictures and video above, the FSP Booster X5 450W adapter uses a similar mechanism for turning on as we saw employed with the Add2Psu. A Molex connector from the primary (i.e. already installed) power supply connects to the back of the secondary power supply (i.e. auxiliary power supply being added) where along with an internal relay both power supplies are turned on at once. Once the two units are connected, users can then mount the Booster X5 450W inside of a free 5.25" drive bay, route the AC power cable for the unit through the mounting bracket in an unused expansion slot and power their system on. As with the Add2Psu setup, this configuration does cost users a Molex connector. Unlike with the Add2Psu though, you do not gain any Molex connectors back from the Booster X5 450W as it only has 4 PCI-Express connectors. Now on the upside, if you have limited room and cannot fit a second ATX12v power supply in your case, but have a free 5.25" bay, or even enough room to stash the unit somewhere else, you can add a second power supply to your system quickly and easily with this product.

As we see in the video above, after connecting the FSP Booster X5 450W to the Zalman ZM-450 via the Molex connector on the ZM-450 and to the wall via the provided AC input cable, both the Zalman ZM-450 and the Booster X5 450W successfully turn on at once allowing users to expand the number of PCI-Express connectors in their system to support things not possible with the original power supply because of either physical or electrical restraints. The biggest downside to this configuration, as we alluded to above, is the fact that all that is gained when using an auxiliary power supply are more PCI-Express connectors, which however is perfect for video card expansions. Users looking for any other expansion should, obviously look elsewhere.

One of the issues that the Add2Psu, the Lian-Li cable, or the auxiliary power supply address is that if either power supply fails; you are left with either a non-functional or marginally functional system. The real chances of this happening are of course going to be dependent on the quality of the power supplies chosen, particularly when using two cheap power supplies with the Add2Psu or the Lian Li cable but also to some extent with the auxiliary power supply idea as well, and the environment in which the products are used. In order to address this issue of tolerance to a single power supply failure, a user would need to be using a product that offers some sort of redundancy, which leads us to our final product today.