Planning to Buy a new graphics card for your PC? - Part 2

With Desktop PCs, there will be a few expansion slots located on its motherboard. Typically they will all be PCI Express slots, but for a graphics card you need a PCI Express x16 slot. There are three versions of this slot, but they are backwards compatible, so a modern PCI Express 3.0 graphics card will work in a motherboard with a PCI Express x16 2.0 slot.

If your PC's motherboard has two PCI Express x16 slots it's most common to use the top one for fitting your new graphics card, but if you're fitting two cards in an NVidia SLI or AMD Crossfire setup, you'll need to use both of them. Check which standard your motherboard supports before investing in a pair of cards, though.

How to know if a graphics card is compatible: length and height

Powerful graphics cards tend to have large fans to keep them cool and this makes them twice as thick as a ‘single-height’ card. The way most computers are built means that the fan assembly will often be underneath the card rather than on top of it, so you’ll need an unused slot - and back plate - directly underneath the PCI Express x16 slot.

You also need to measure the distance from the back plate to any components which would block a long graphics card at the front of your case. Don’t forget that some cards have their power sockets on their back edge rather than the side, so you’ll need to add about 30-40mm to the length of your chosen card to guarantee it will fit comfortably.

If you’re unsure how long a card is, ask the manufacturer, seller or try pc forums and blogs to find someone who owns that card already and can confirm how big it is.

Next Month: How to know if a graphics card is compatible: power requirements