5 useful PC upgrades to plug into your unused PCIe slots

1. PCIe graphics cards

If you have a desktop PC with at least an mATX motherboard or larger, chances are you have access to multiple PCIe slots.

If so, the top slot likely runs at PCIe x16, meaning 16 data lanes, which is ideal for high-bandwidth add-ins like a graphics card. And if you have a second slot, it likely runs at PCIe x8. That’s half the speed, and that’s why the top slot should always get your GPU. Some smaller PCIe slots run at x1 or x4, and these are meant for low-bandwidth add-in cards (see below).

But everyone already has a graphics card, right? In fact, the one PCIe add-in that most people know about is the graphics card, to the degree that some even believe the PCIe slot is only for GPUs.

There was a time when multi-GPU setups were the next big thing for gaming, but those have been defunct for a while now. Nvidia’s SLI tech for linking together GPUs is no longer supported.

But that doesn’t mean you can’t utilize a second high-performance GPU in your PC for other, non-gaming purposes. Graphics and 3D apps, together with video editing software like DaVinci Resolve, can effectively use more than one GPU for boosted performance.

Indeed, resource-intensive tasks are the best use case for multiple GPUs now. But for gaming or streaming, don’t even think about throwing in a second GPU. You might think more is merrier, but it usually causes more trouble than it’s worth, not to mention the extra space and PCIe slots taken from other potential PCIe add-ins.

If you do decide to add a second GPU to your system, there are some important caveats to be aware of. For starters, on most ATX motherboards, having two GPUs will likely cause each one to only run at x8 speeds max, even when plugged into x16 slots. Only a few select workstation or high-end models can do more.

Moreover, if you have two GPUs for video editing or 3D rendering, keep a careful eye on thermals. With GPU coolers being so large these days to accommodate their powerful performance, a blower-style approach may be best for multi-GPU setups. The top GPU is at most risk of decreased airflow, which can lead to overheating with inadequate airflow.

If you water cool your GPUs, then you might even be able to go beyond two GPUs — if your motherboard supports it. Some apps can take advantage of two or more GPUs, and the thinner form factor plus water-cooled heat dissipation minimize overheating risk.

2. PCIe storage cards

Other than a graphics card, storage might just be the most useful way to fill your empty PCIe slots. Ultra-fast PCIe storage cards have popped up in the market, both for gamers and workstation users. Some of these NVMe PCIe add-in cards can even run at x16 and support up to eight NVMe drives in an array for blisteringly fast performance.

With new games crossing the 100GB mark these days, having terabytes of storage space isn’t only something for video editors and data hoarders to worry about anymore.

If your motherboard has extra PCIe slots after accounting for your GPU(s), then consider adding tons of utility with a PCIe storage card. There are PCIe NVMe cards as small as a singular drive, which take up minimal room while adding ample amounts of high-speed performance.

Some high-end motherboards, such as the ASUS ROG Hero line, even include a PCIe NVMe card in the box for added storage potential. If you take full advantage of your motherboard’s PCIe allocation, you can unlock some serious storage gains with great performance.

And there’s another significant boon to using internal PCIe storage cards: they pack neatly into your PC, relieving you from the clutter that comes from having tons of external data drives. While portable SSDs are great for some extra storage, you have to deal with cables and they take up physical space. PCIe storage is out of sight, out of mind.

Not only that, but internal PCIe storage is faster. Even the fastest on-the-market external drives max out at the 40Gbps speeds of Thunderbolt 4 and USB4, equating to 5,000MB/s. Meanwhile, ubiquitous PCIe Gen 4 drives can reach a theoretical max of 8,000MB/s and PCIe Gen 5 drives can go up to a blazing-fast cap of 14,000MB/s.

And PCIe storage isn’t restricted to just NVMe. Other SSDs and storage types are possible, and they can even be put into RAID setups for data backups. It’s a cost-effective alternative to pricier mainstream solutions that rely on Thunderbolt or USB-C connections.

If you’re thinking about getting a PCIe storage card but aren’t sure where to start, here are two solid options: Asus Hyper PCIe 4.0 expansion card supports four Gen 4 NVMe drives and Asus Hyper PCIe 5.0 expansion card supports up to four Gen 4 or Gen 5 NVMe drives. Always check motherboard compatibility before buying a PCIe card.

3. PCIe audio and sound cards

You might think that sound cards and other audio add-ins are defunct… and you wouldn’t necessarily be wrong. Few people really need a PCIe sound card these days.

But they still exist, mainly used in niche areas like professional audio work or specialized gaming sound cards. Even the Apple Mac Pro has as its primary feature the ability to use PCIe slots, allowing for sound and video folk to get the most utility out of their system.

A sound card, especially a PCIe one, is still useful when you need high-quality audio that can’t always be produced or replicated by a motherboard. These PCIe sound cards often have extra inputs and even surround sound capability, and they’re less likely to run into audio interference since it’s a separate unit from your motherboard.

PCIe sound cards are typically small, so they take up a minimal amount of space and can work just fine even in smaller PCIe slots, leaving your larger PCIe lanes for other high-bandwidth add-in cards.

But, again, discreet sound card options remain a niche market and continue to grow more niche by the year. If you’re an audio professional, you likely already know about pro-grade PCIe audio cards for your workflows. But if you’re just an audiophile, consider adding a PCIe sound card to get even better audio out of your system.

High-end PCIe audio interfaces, like the HDX PCIe Core Card by Avid Pro Tools, can run into the thousands of dollars. They are, after all, designed for audio professionals involved in real-time mixing and processing engines. For large and extensive audio projects, a PCIe add-in with near-zero latency is extremely important and worth paying up for.

For audiophiles, you have consumer-oriented options like the budget-friendly Creative Sound Blaster Audigy FX PCIe 5.1 sound card up to the enthusiast-class Creative Sound BlasterX AE-5 Plus hi-res gaming sound card. It’s an effective way to fill your PC’s unused PCIe slots.

4. PCIe capture cards

A capture card is a device that takes in an external audio/video source and processes that input, whether for recording, editing, or uploading to a streaming site like Twitch or YouTube. For example, a capture card would be great for capturing footage from a camera or gaming console in real time and making it available to your PC.

PCIe slots are great for capture cards because the ultra-fast data speeds are perfect for high-resolution, high-frame-rate video that would otherwise overwhelm. One of the more popular PCIe capture cards on the market is the Elgato 4K Pro, a staple for gamers who like to record and stream themselves playing games.

While USB capture cards like the Elgato HD60 X exist, internal PCIe capture cards don’t take up any desktop space, have much lower latency, and can handle much higher resolutions and frame rates. If you’re a gaming content creator, it’s one of the most useful PCIe additions.

Capture cards are also for professionals, and PCIe varieties are the best when it comes to that. For example, the DeckLink 8K Pro G2 capture card by Blackmagic Design is among the best, able to capture 8K footage at high frame rates in professional formats, complete with 12-bit RGB 4:4:4 video and full Rec. 2020 color.

Pros would be amiss without the powerful features and specs found in such PCIe solutions, and there’s more than this out there. Once again, most home users won’t need to spend this much on one, but consumer-grade alternatives often share the same PCIe DNA.

5. PCIe network and USB cards

If you really don’t know what else to do with your empty PCIe slots, consider adding more USB ports via PCIe. Whether your motherboard lacked ports out of the box or you plugged them all up with accessories and peripherals, a PCIe USB expansion card is one way to get more ports (or a Thunderbolt PCIe card, if your motherboard supports it).

But why stop there? Maybe you’d be better off with a PCIe network card. While most motherboards now pack Wi-Fi out of the box, network PCIe cards can still be useful. They can add Wi-Fi and Bluetooth capabilities for cheap, allowing you to forego Ethernet as needed. And they aren’t that expensive, either. The TP-Link AX3000 PCIe card can often be had for around $35, and it supports Wi-Fi 6 and Bluetooth 5.2.

You’ll find all kinds of PCIe network cards with various speeds, but this is also a good opportunity to upgrade to Wi-Fi 7. For example, the TP-Link BE9300 PCIe card is a tri-band adapter that supports both Wi-Fi 7 and Bluetooth 5.4, cutting-edge tech with cutting-edge speeds. (Learn more about the new Wi-Fi 7 standard and why you’ll want it.)

As you can see, PCIe slots offer several useful ways to step up your PC and add new functionality. If you have empty PCIe slots on your motherboard, consider filling them so you get the most out of your system!