R9 390 Power Consumption Guide

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Despite its age, the R9 390 is a graphics card that packs a serious punch. When it was released in 2015 it was targeted at a niche audience of gamers who wanted a really powerful card, and it’s still going strong – capable of running many of the latest games at quality frame rates.

R9 390

But one of the quirks of the R9 range of graphics cards is its unusually high power consumption for the time. It’s a card that does not scream efficiency – but just how much power does it use, and what power supply will you need to run it?

Let’s take a look.

How Many Watts Does An R9 390 Use?

When being used for gaming or to render videos live, the R9 390 graphics card will typically use around 277 watts of power. That can increase significantly when you put it under extra duress, up to a maximum of around 365 watts.

That’s comparable to many of the top-end graphics cards released since 2020 – including cards that are much more powerful than the R9 390 and that are capable of doing so much more. This is a bit of a drawback for a card at this level – if you’re going to be burning through over 300 watts then you want to make sure you’re getting value.

When fully idle – meaning you aren’t using your PC for anything graphical, such as you’re browsing the web or writing up some work reports – the card uses 9 watts of power. That’s about average for modern cards too some may use more but only by a couple of watts at most.

What’s most unusual is just how much power the R9 390 needs when you connect a second monitor or when you use it to watch pre-rendered video such as on YouTube or a Blu-Ray. If you connect a second monitor it shoots up to 71 watts, while it’s 73 watts for watching videos.

This is exceptionally high especially for adding a second monitor – most modern graphics cards will only use 15-20 watts for that. This tells you just how inefficient the R9 390 is (source).

How Many Watts Does An R9 390 Use Per Hour?

When gaming, expect the R9 390 to use around 277 watt-hours per hour, which can also be expressed as 0.277 kilowatt-hours per hour. Over the course of an average week where a user spends 8.5 hours gaming, that works out to 2.4 kilowatt-hours in a week.

It’s always better to look at the power consumption of a device in kilowatt-hours (just divide the watt-hours by 1000) as that’s how we’re charged for electricity – one kilowatt-hour is one unit. The average price in the US for kilowatt-hours is $0.14 so every week the R9 390 would be costing you around $0.34 in electricity.

But of course, that is just for the graphics card – not for the entire PC. And when you’re trying to work out which power supply you need you should consider all of the components you have installed.

True the graphics card will normally be the biggest power draw – and with the R9 390 that’ll be by some distance. But a good processor, a gaming motherboard and other parts will all add up as well.

Read more: How many watts does a Gaming PC use?

The other thing to consider is that the $0.34 is only for while you’re gaming. Most people use their PCs for more than 8.5 hours per week – typically it’s close to 24 hours a week for US citizens. So you also need to consider the power consumption of the graphics card during that other 15.5 hours when you aren’t playing games.

It’s likely to be minimal if you’re only using a single screen, but with this card being inefficient it could be costly if you have a second monitor. So, bear that in mind when estimating your electricity costs for your PC.

What Power Supply Do I Need For An R9 390?

The minimum recommended power supply for a PC with an R9 390 graphics card has a capacity of 550 watts. Ideally, you would aim higher, to avoid your PC restarting with excessive power spikes – 650 watts or better would be suitable.

When you’re calculating which power supply you need, you want to make sure it has around 20% more than the sum total of the consumption for all your PC parts combined. This allows for any sudden power spikes without suddenly overloading the PSU and causing it to restart or shut down.

The Best Power Supply For An R9 390

The best power supply for an R9 390 graphics card would be one that can provide 650 watts of power or more. Make sure you choose one from a reputable brand and that it’s rated at least 80+ Gold for efficiency.


  • Fully Modular to reduce clutter and improve airflow
  • 80 PLUS Gold certified
  • 7 Years of EVGA Customer Support

This 650-watt power supply from EVGA is a great choice. EVGA is a well-known brand that produces high-quality parts, and you’ve got plenty of capacity with this card to handle anything your R9 390 decides to throw its way.

It’s also rated 80+ Gold, which means you aren’t paying for a load of wasted electricity that your PSU is converting into unnecessary heat.

Read more: Power Supply Ratings Explained

Plus, it’s fully modular. This means you only need to add in the cables that you’re using for your setup – they aren’t all fixed into the supply. You won’t have to find somewhere in your case to stuff unused cables and you’ll keep the air flowing through the case nicely, keeping the system cooler and working more efficiently.

What R9 390 Power Cable Do I Need?

The R9 390 has both an 8-pin and a 6+2 pin connector and you should connect both of these to the power supply. Each cable is capable of handling around 150 watts of power, so both are needed to provide sufficient energy to the graphics card.

Some PSUs come with split cables – one cable running from the PSU that splits into two connectors. Don’t use these, as they won’t deliver the power that the card needs if you want it to play the latest games.

R9 390 FAQs

Is 500 watts enough for an R9 390?

A 500-watt power supply probably isn’t enough for an R9 390 graphics card. It might work if your other components are entry-level but the minimum recommended PSU is 550 watts and ideally you would be aiming for a 650-watt supply instead.

Is the R9 390 power efficient?

The R9 390 can’t be considered power efficient. It’s an older card that, while still capable of playing the latest games, uses a lot of power to do so. It draws an extreme amount of power when used idle with more than one screen compared to other cards.

Is a 650-watt power supply enough for an R9 390?

A 650-watt power supply is likely the sweet spot for an R9 390 graphics card. It’s above the minimum spec and should easily handle the card in a mid- to high-end system, but with enough leeway to handle any power spikes – even more likely with the older, inefficient card.

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