A new graphics card is usually the single biggest jump in gaming performance you can give a PC. It's also the upgrade most likely to run into the limits of the power supply (PSU) that came with it. A PSU that's too small, too old or missing the right connectors can mean crashes under load, a PC that shuts off mid-game, or a card that won't plug in at all.
Here are the four things we check at our Midland workshop before fitting a new card, and you can check most of them yourself before you buy.
1. Wattage: start with the card maker's recommendation
Every graphics card has a recommended minimum power supply wattage on its specification page, from NVIDIA, AMD or Intel and from the board partner (ASUS, MSI, Gigabyte and so on). That figure already allows for a typical processor and the rest of the system, so treat it as the floor, not the target.
To find what you have now, switch the PC off at the wall and look at the label on the side of the power supply inside the case. The wattage is printed there along with the brand and model. If you can't see it without taking the PC apart, the original build invoice or the PC maker's spec sheet often lists it.
Some headroom above the recommendation is worth having, especially with a high-end processor. Modern graphics cards can draw short spikes of power well above their rated figure, and a power supply running near its limit is the one most likely to trip and switch off when that happens.
2. Connectors: does it have the right plugs?
Wattage is no use if the cables don't fit. Check the power connectors on the card you want against the cables your power supply has:
- 8-pin PCIe (often labelled 6+2): most cards need one, two or three of these.
- 16-pin 12V-2x6 (the updated 12VHPWR): used by many recent NVIDIA cards and some others. Newer ATX 3.x power supplies have this cable built in. Older ones need the adapter that comes in the graphics card box.
If you use a 16-pin connector, push it in until it's fully seated and don't bend the cable sharply right at the plug. A connector that isn't fully home is a known cause of overheating at the plug.
3. Use separate cables, not one split cable
Many power supplies include PCIe cables with two 8-pin plugs on one lead. For a card that needs two or more 8-pin connectors, it's better to run a separate cable from the power supply to each socket where you have enough cables. Spreading the load reduces heat in the cable and gives the card a steadier supply under heavy gaming load. Your power supply and graphics card manuals will say what they recommend.
4. Age and quality matter as much as the number
A cheap or ageing power supply may not deliver its label wattage cleanly any more. Warning signs are a PC that restarts or switches off under gaming load but runs fine on the desktop, coil whine or a burning smell, or a unit that's been through many years of heavy use. A no-name unit with a big number on the label is a risk to every part in your PC, not just the new card.
When we fit a power supply we use parts from the same trusted brands as our custom gaming PCs, and we route the cables properly so they don't block airflow.
Don't forget the case. Modern graphics cards are long and thick. Measure the space in front of the card slot, and check the card won't block your drive bays or front fans, before you order.
Is a new power supply worth it, or is it time for a new PC?
If your processor and motherboard are reasonably recent, a graphics card plus a quality power supply is usually great value: you get most of the gaming gains of a new PC for part of the cost. If the processor is also several years old, a fast new card can end up waiting on it, and you may be better off putting the money towards a new build.
Our free gaming PC bottleneck checker helps you work out which part to upgrade first, and our PC builder lets you send us a budget for a new build to compare against.
Let us check it for you
If you'd rather not open the case, bring the PC to our Midland workshop. We'll check the power supply's wattage, connectors and condition, the space in your case and your processor, then tell you what the new card needs. When we fit the parts, we stress-test the PC under load before you take it home. Already seeing crashes or glitches with your current card? Read our guide to GPU artifacting or see our desktop PC repairs and upgrades.