Planning to Buy a new graphics card for your PC? - Part 3

The Power Requirements

Even if you have PCI Express x16 slot and plenty of room, you’ll need extra power for most modern graphics cards.

Your power supply will most likely have PCI-E power connectors, but they may be bundled up and tied out of the way if no graphics card is currently fitted. These connectors are usually black, marked as PCI-E and have six pins in a 3x2 arrangement. If your Power Supply Unit does not have these, you can buy adaptors which connect to the standard four-pin power or SATA connectors.

Be careful with graphics cards that require two PCI Express power connectors as each of these should be connected to a different 12v rail of the power supply. On most Power Supply Units this means connecting each of the two adaptors to a different ‘daisy chain’ of power connectors and not to the same chain.

Finally, make sure your power supply is powerful enough to work with the existing components in your PC. This can be tricky to work out, but a good rule of thumb is that high-end graphics cards will require at least a 600W PSU and may be even more.

It’s wrong to assume that a Power Supply Unit can output its maximum power rating continuously, so you could run into problems if your components are drawing more power than around 80% of the power supply’s top rating.

It’s fairly easy to check how much power a graphics card draws by searching online for the make and model you are planning to buy.