Just buy a new PSU if you don't have the appropriate power connectors available.

It's also important to note here that while 4-pin Molex to 6-pin PEG power adapters exist, as do 6-pin to 8-pin adapters, you really shouldn't use these! Melted wires, short circuits and even fires have been started with such shenanigans. If you have a PC from a large OEM (eg, something from Dell, HP, or Lenovo), you might not even be able to swap out the power supply for a newer model with the required 6- or 8-pin connectors. 6-pin PEG connectors have been around much longer, but some budget power supplies still omit them. If you have a PC that was built before 2015, there's a good chance your power supply won't have any 8-pin PCI Express Graphics (PEG) power connectors available, which are used on many of the faster cards today. Power requirements are another major sticking point. These are approximate values, with recommendations based on having power to spare. Subtracting 20mm from your measurement and buying a card that's shorter than the resulting length should do the trick. Even if you measure 300mm of clearance and a graphics card says it's 300mm long, it may be too snug a fit. We recommend giving yourself some wiggle room as well. A tight fit at the back of your GPU could make it impossible to connect the power cables. Most cards have them on the top, but some (eg, Nvidia's RTX 2060 Founders Edition) have them on the back. Also pay attention to where the PEG connectors are located on whatever GPU you purchase. It doesn't matter if it's drive bays, fans, or the front of the case - just measure near your primary PCIe x16 slot (the one closest to the CPU cooler), as that's where your graphics card should go.

To determine how long your graphics card can be, measure from the expansion slots on your case to whatever part is most likely to obstruct the graphics card on the other end. We recommend going old-school and using a ruler or measuring tape - it will likely take less time and give you more accurate information. For pre-built PCs, you probably won't have it or be able to find the information online.

To find out how big your GPU can be, you could try looking at your case manual, assuming you have that.

Metal compatible video cards