Short answer: graphics cards draw short spikes of power, for fractions of a second, well above their rated figure. Older or undersized power supplies can see these as a fault and shut down. ATX 3.0 and 3.1 units are built to handle them.
What a spike is
A graphics card’s power draw jumps around constantly as the load changes. Most of the time it stays near its rating, but for tiny moments it can go far above. These are called transients or power excursions.
How big they get
MSI measured a whole PC with an RX 9070 XT averaging around 455W to 501W in games, with peaks of 864W to 1029W. The peaks were roughly double the average.
Why they crash PCs
A power supply has protections that shut it down if the load goes beyond what it can handle. Older designs weren’t built for spikes this big. They can mistake a normal spike for a fault and switch off. To you, that looks like the PC turning off mid-game, with no warning or error.
If that’s happening to you, see PC shuts off under load.
What ATX 3.0 changed
Intel’s ATX 3.0 specification added new requirements so power supplies cope with the power excursion limits set for PCIe 5.0 graphics cards. It also brought in the 16-pin connector, which can deliver up to 600W to a graphics card. ATX 3.1 refined the connector. More in the ATX 3.1 guide.
That’s why every unit on my list supports ATX 3.0 or newer.
How to protect against spikes
- Buy an ATX 3.0 or 3.1 unit. It’s the simplest fix.
- Size it properly. Follow the recommended size for your card in the wattage guide.
- Add headroom if you have a top processor or an overclocked card.
- Use separate cables for each graphics card power socket.
Spikes versus reviews
Lab reviewers test how well a power supply holds its voltages when the load jumps suddenly. They call it transient response. It’s one of the measurements behind the comments in my product pages, such as “a clean response to sudden load changes”.
- Clean transient response · Tier ACorsair RMx Shift80 Plus Gold · Fully modular · ATX · 750/850/1000WLab reviewers praised its response to sudden load changes.Check 850W price
- ATX 3.1 all-rounder · Tier ACorsair RMx (2024)80 Plus Gold · Fully modular · ATX · 750/850/1000WQuiet, well reviewed and widely available.Check 850W price
Questions
Do spikes damage my parts?
Not usually. The risk is that a weak power supply shuts down, causing a crash.
Do I need ATX 3.0 for an older graphics card?
It’s not required, but it’s the safer choice and every unit on my list has it.
Why does my PC only shut off in some games?
Some games load the graphics card more heavily, or swing the load more sharply, which causes bigger spikes.
Will undervolting help?
It can lower peak power, which may stop shutdowns on a borderline power supply. Replacing an undersized unit is the real fix.
What is transient response?
How well a power supply holds its voltages steady when the load jumps suddenly.
Sources
- MSI: best PSU for AMD RX 9070 XT
- Intel: new ATX power supply specifications
- Corsair: ATX 3.0 vs ATX 3.1
- HWBusters: Corsair RM850x Shift ATX 3.1 review
As an Amazon Associate I earn from qualifying purchases. Prices and stock are on Amazon.