Short answer: you need a new power supply if it’s too small for the new card, lacks the right connectors, or is old and past its warranty. If it passes all four checks below, keep it.
Find your current power supply
Before you start, you need the brand, model and wattage. The quickest ways to find them:
- Look at the label on the side of the power supply. You may need to remove a side panel.
- Check your order history or the box if you still have it.
- If you bought a prebuilt PC, check its spec sheet. Some only list the wattage, so the label is more reliable.
Check 1: wattage
Look up your new card in the wattage guide. These are MSI’s recommendations for a standard gaming build:
| New graphics card | Recommended size |
|---|---|
| RTX 5090 | 1000W |
| RTX 5080 | 850W |
| RTX 5070 Ti | 750W |
| RTX 5070 | 650W |
| RX 9070 XT | 750W to 850W |
Add about 100W if you have a top processor or you overclock. If your unit is at or above the figure, it passes this check.
Check 2: connectors
Many new Nvidia cards use a single 16-pin connector. ATX 3.0 and 3.1 units have a native cable for it. Older units need the adapter that comes with the card, which takes several 8-pin cables from the power supply. That adds more connections that all have to be fully seated.
AMD cards vary: MSI notes RX 9070 XT models use two or three 8-pin plugs or one 12V-2x6. Check the product page for your exact card.
- If your power supply has enough separate 8-pin graphics card cables for the adapter or card, it can work.
- If you’d need splitters or extra adapters to get there, replace it.
Read the ATX 3.1 guide for how to fit the 16-pin plug safely.
Check 3: age and warranty
A power supply that’s past its warranty has given you good service, but it’s also the oldest part in the build. A big graphics card upgrade adds stress, and newer cards draw short power spikes well above their rating. ATX 3.0 and 3.1 units are designed for those spikes. Older units can see them as a fault and shut down.
Check 4: is it a good unit?
Look up your model on my tier list. If it isn’t there, search for a lab review. If you can’t find one, or it came free with a case, it’s safer to replace it.
Worked examples
| Current setup | Upgrading to | Verdict |
|---|---|---|
| 650W Gold, 4 years old, two 8-pin cables | RTX 5070 | Keep it. It meets 650W and has the cables |
| 650W Bronze, 6 years old | RTX 5070 Ti | Replace. It’s below 750W |
| 750W Gold ATX 3.0, 2 years old | RTX 5070 Ti | Keep it. Right size with a native 16-pin cable |
| 850W Gold, no 16-pin cable, 8 years old | RTX 5080 | Replace. Past warranty and needs an adapter |
| 1000W ATX 3.1 from my list | RTX 5090 | Keep it. Meets MSI’s figure |
Signs you’ve outgrown it
If you’ve already fitted the new card and the PC shuts off or restarts during games, the power supply is the first suspect. See signs your power supply is failing for how to check.
If you do need a new one
- For an RTX 5090 · Tier ACorsair RMx (2024)80 Plus Gold · Fully modular · ATX · 750/850/1000WThe 1000W version gives the headroom MSI recommends.Check 1000W price
- For an RTX 5080 · Tier ACorsair RMx Shift80 Plus Gold · Fully modular · ATX · 750/850/1000W850W, Tier A, very quiet in lab tests.Check 850W price
- For an RTX 5070 Ti · Tier ACorsair RMx (2024)80 Plus Gold · Fully modular · ATX · 750/850/1000WThe 750W version, quiet at everyday loads.Check 750W price
- For an RTX 5070 · Tier ASeasonic Core GX ATX 380 Plus Gold · Fully modular · ATX · 650/750/850WCompact and solid at 650W.Check 650W price
- For an RX 9070 XT · Tier Bbe quiet! Pure Power 13 M80 Plus Gold · Fully modular · ATX · 750/850/1000/1200WQuiet, with headroom at 850W.Check 850W price
Remember to replace every modular cable with the new unit. See why. More picks for each card in the best power supply for your graphics card.
Questions
Is an adapter safe?
Use the native cable where you can. If you must use the adapter that came with the card, make sure every connection is fully seated.
Can I use one 8-pin cable with two plugs on it for my graphics card?
Where you have enough separate cables, use them instead. It spreads the load across more wires and connectors.
My power supply is the right wattage but 10 years old. Should I replace it?
If it’s past its warranty and you’re fitting a much more powerful card, I would.
Do I need ATX 3.1, or is ATX 3.0 fine?
ATX 3.0 is fine. ATX 3.1 is a refinement, mainly to the connector.
Will a bigger power supply make my new card faster?
No. It only needs to be big enough. Extra wattage gives headroom, not performance.
Sources
- MSI: recommended PSU table for Nvidia 30/40/50 series
- MSI: best PSU for AMD RX 9070 XT
- Corsair: ATX 3.0 vs ATX 3.1
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