Why You Should Try A Digital Power Supply For Your Next PC Build

Photo: NZXT

I always like knowing what’s going on with my PC, but I tend to only focus on its cooling capabilities, since that directly affects whether my system sounds like a purring kitten or a jet engine while I’m working (or gaming). However, I’ve always been curious to know how much power my system draws, since I tend to leave it on longer than I probably need to throughout the day.

While it’s easy to measure the power draw of any appliance by picking up a handy reader—the Kill A Watt, for example, or something quick and easy like the Belkin Conserve Insight I use—you might want to consider a more fun and thorough solution if you’re looking to upgrade your desktop system (or build a brand-new one). I’ve been playing around with NZXT’s E850 digital power supply and system-monitoring CAM software, and both have taught me a lot about my system’s power requirements.

Power supplies are sexy

NZXT’s digital power supply works like any other power supply, save for one slight modification. In addition to the normal bevy of modular connections you use to power your various components, the power supply also has a standalone USB-C connection. This plugs directly into one of the free USB headers on your motherboard (assuming you have one), and allows the power supply to output data on what it’s doing to NZXT’s accompanying (free) CAM software.

In general, CAM is similar to tools like Speedfan, CPU-Z, GPU-Z, HWMonitor, or whatever other apps you use to monitor your PC’s components. On its primary screen, you can get a quick read of key details: CPU temperature, load, and your cooler’s fan speed; your GPU’s temperature, load, and fan speed; and your RAM use. Easy stuff.

Screenshot: David Murphy

Assuming you’ve connected up your NZXT power supply correctly, you’ll also get a special section dedicated to power data. Click on the zappy lightning bolt icon, and you’ll see an updating measurement of how much juice your system is using, split into separate measurements for your CPU, your GPU, and any other devices connected to your power supply (hard drives and case fans, for example, which all get lumped together into an “others” category.)

Screenshot: David Murphy

You can’t adjust the little line chart to give you a bunch of historical data, or even an hour’s worth of measurements (alas), but you can click on the “Advanced” tab to examine the voltage and amps of your power supply’s rails. This is also where you can set up Over Current Protection, which can automatically shut down your system in the event of an unexpected short.

A separate section in the CAM software even allows you to adjust the profile of the power supply’s fan, in case it’s too loud while you’re trying to work. I set mine to the “quiet” default and never looked back, since my graphics card is the real noisemaker on my system anyway.

How accurate are a power supply’s readings?

I was pleased to find that the measurements from NZXT’s power supply and my aforementioned Belkin power meter were pretty close to one another. In my configuration, the power supply was underreporting by around 20w on average—likely the amount of power it draws for its fan and general operation, which it doesn’t count in its measurements.

(In case you’re curious, I tested this hypothesis by manually cranking the power supply’s fan to maximum. As I expected, the Belkin power meter’s reading shot up even more compared to the power supply’s reading. It returned back to the regular “20w overage” when I turned the power supply back to “quiet” mode.)

This presents an interesting trade-off. If you want a true, every-watt-counted measurement of how much power your desktop PC draws, a device like the Kill A Watt is your best bet. However, if you want a more detailed look at how much power your system’s components draw at any given time—or over time—a digital power supply is ideal. I’m going to stick with the latter... and just not look at that number, nor think about what it’s costing me, when I’m having an all-day gaming binge.


Comments

    I will happily second this recommendation. I switched to a Corsair AX760i several years ago and the extra data you gain through it's reporting is terrific when it comes to decision making. The biggest thing it confirmed for me was the BS that so many tech sites and so called tech experts were spouting about needed 1KW (or bigger!) PSUs. Even under max load while gaming I've yet to see the PSU hit even 50% load. So a 1KW PSU would be a massive waste of money.

    The Corsair, like the NZXT in the article doesn't report exactly that same as a power meter between it and the wall will, but it's pretty accurate.

      One thing you need to consider regarding this though is the efficiency of the psu. Most psus only hit peak efficiency around the 40-60% usage area, so if you require 500w then a 1kw will be most efficient.
      obviously this also depends on how much that matters to you, since the cost difference between those 2 psus could be significantly more than any potential savings over its lifespan. but if youre gonna go for a psu with 80+ certification rather than a cheap and nasty, may as well get the best fit.

        Well it depends on the efficiency rating curve of the individual PSU, since some of them vary very little between even 20%-100%. A platinum rated one would be something like 90% efficiency at 20% load, 92% efficiency at 50% load and 90% efficiency at 100% load. So it's not going to make a tremendous difference in terms of power used.

        That said, the Corsair I have slots nicely into the 40-60% range that a lot of people talk about, sitting at about 50% load while gaming. That said it's 80+Platinium meaning it should get at least the efficiency I mentioned above. Now if I was going dual Vega 64 cards I'd probably want to get a 1KW PSU since they're rated at something like 300W *each* but for a GTX1070 that's only 150W even a 760w PSU is nearly too big.

    Different games use different amounts of power, 650w at the wall is my average gaming but I'm not about to worry if it hits 900w at the wall and no gamer on here would care we just want the best gaming possible. No gamer worries about power we want silence and the best graphics possible at 60fps min.

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