Most beginners may identify the high-speed PCI Express sockets on motherboards as the interface to attach discrete graphics cards to PCs. However, these slots can also be used for a handful of expansion cards. If you’re unfamiliar with the term, these are optional accessories that can be plugged into the PCIe sockets to add new ports or integrate additional functions into your PC.

For those with full-sized ATX motherboards, it’s possible to have more than one PCIe socket ready for use even after slotting the humongous current-gen GPUs. So, here are five neat devices that you can add to your vacant PCIe slots.

5 Sound cards

Only useful in select cases

Back in the day, sound cards were practically essential for any PC user. Unlike modern-day mobos, even the most premium motherboard released before the late 2010s had terrible onboard sound. So, the only way to get rich quality audio was to invest in a dedicated sound card and plug all your sound devices into it.

With the onboard sound provisions getting noticeably better, sound cards have become a rather unnecessary peripheral for the average user. The reason why these cards lie at the bottom of the list is that a DAC + amp combination is far cheaper than a sound card and provides more-or-less the same quality audio. That said, they do serve some utility for audiophiles and can be a worthwhile purchase if you find a used sound card at bargain prices.

4 Capture cards

Great for console streamers

In the past, another PCIe device that saw extensive usage was the capture card, as older PC setups weren’t powerful enough to support high-quality video streams. As a result, professional streamers often resorted to dual-PC setups, with a secondary system equipped with a capture card to handle low-latency streams from their gaming machines.

Nowadays, capture cards may not be as necessary for the average streamer, but they’re still a decent option for latency-free streaming. But if you’re a console streamer or a professional video editor who needs to capture high-fidelity video output from high-end DSLR cameras, capture cards are still a decent purchase even in 2024!

3 USB expansion cards

For those running low on unoccupied USB ports

If you’re a proud owner of multiple accessories, it’s easy to run out of ports on your motherboard and front panel. That’s where USB expansion cards come in handy: by plugging in an empty PCIe socket, you can extend the number of ports available for you to use.

Heck, they’re also quite useful if your motherboard lacks certain connections. For example, many budget mobos may skimp out on USB Type-C ports, making USB expansion cards a lifesaver when you need to plug in peripherals that use this high-speed interface.

2 SATA/M.2 expansion cards

There’s no such thing as too many drives

Arguably the most useful accessory for data hoarders, SATA and M.2 expansion cards let you expand the number of ports available for your storage drives. While this may not sound like a big deal for ATX boards that feature plenty of SATA ports alongside a couple of M.2 slots, the situation is quite different if you’re using SFF systems. In fact, systems with mini-ITX and mATX motherboards can become powerful home servers once you outfit them with these expansion cards. While we’re on the subject of home labs…

1 Network Interface Cards

For high-speed Ethernet speeds and Wi-Fi connectivity

Although the average NAS enthusiast and home lab user may be content with 1GbE connections, you might want to upgrade to a faster NIC if you’re using your server for anything other than media streaming or archiving old data in slow HDDs. I’ll admit that not everyone needs to drop obscene amounts of money on a 10GbE connection. But I daresay that if you’re planning to establish a home server, a 2.5G/5G NIC is borderline essential to avoid bottlenecking your data speeds.

Plus, not every budget motherboard comes with onboard Wi-Fi — and even the ones that do tend to be limited to a 2.4GHz standard. Once you include NICs with built-in Bluetooth connectivity, it's easy to see why these cards lie at the top of the list.

Which of these cards do you consider a must-have accessory?

Having choked the PCIe slots on both of my ATX systems, I can confirm that USB expansion cards, PCIe-to-SATA adapters, and NICs are indispensable peripherals in my computing setup. Of course, there are a couple of other obscure PCIe devices out there, though they aren’t quite as useful as the ones I’ve highlighted here.

For instance, RAID controllers were often the lifeline of NAS systems a couple of years ago. But with software RAID growing in popularity and utility, there aren’t many cases where you’d want to switch to hardware-controlled RAID setups. If you’re working with legacy peripherals, it may be worth installing PCIe-to-serial or PCIe-to-PS/2 adapters into your motherboard. And then there were first-party accessories, like the HTC Vive wireless adapter that you could plug into a PCIe slot to free the company’s premium VR headsets from the confines of cables.