OCuLink vs USB 4.0: Best eGPU for Mini PC in 2026

Mobility is increasingly important for both work and leisure, which is why mini PCs are spreading through the market like never before. These compact devices are even easier to transport than a laptop and offer extraordinary performance thanks to their high-end hardware: hardware that can also be supplemented with external devices such as an eGPU.

When it comes to connecting these external devices, there are two essential standards: USB 4.0 and OCuLink. Both are very current, but they have different characteristics and apply to different use cases. That’s why we’re going to show you below how OCuLink differs from USB 4.0 and which standard is right for you in each case.

What is USB 4.0?

USB 4.0 is the new USB universal connectivity standard for transferring data between computing devices at high speed. It’s based on Thunderbolt 3, uses a USB-C port, and was launched in 2019. In addition to its high speed—up to 5 GB/s, or 10 GB/s in its USB4 v2 variant—it’s ideal for its compatibility with all types of devices.

• Speed: Up to 5 GB/s, or 10 GB/s in its USB4 v2 variant.
• Port: USB-C.
• Video: Allows video transfer up to 8K.
• Charging: Allows charging up to 100 W.

What is OCuLink?

For its part, OCuLink is an earlier connectivity standard—launched in 2015 and updated in 2017—designed primarily for connecting external PCI devices. It doesn’t allow device charging or video transmission and has much more limited compatibility because it uses a PCI port instead of USB-C.

• Speed: Up to 4 GB/s in its PCIe 3.0 x4 variant, and 8 GB/s with PCIe 4.0 x4.
• Port: PCI.
• Video: No.
• Charging: No.

👉 More information about: PCIe 4.0 vs 5.0: The Ultimate Guide In 2026

OCuLink vs USB 4.0

OCuLink and USB4 both carry PCIe data to external devices, but they take fundamentally different routes to get there. OCuLink is a direct PCIe passthrough link defined by PCI-SIG, exposing host lanes to an external device with almost no protocol overhead. USB4 is a tunnelling standard: it encapsulates PCIe, DisplayPort and USB 3.2 traffic inside a single USB-C link. That distinction explains nearly every practical difference between them, from raw eGPU throughput to hot-plug behaviour and cable convenience.

Aspect	OCuLink	USB4
Standard body	PCI-SIG (SFF-8611 / SFF-8612 connector)	USB-IF, built on donated Thunderbolt 3 protocol
Connection method	Direct PCIe passthrough, no translation layer	Tunnels PCIe, DisplayPort and USB 3.2 over one link
Peak link rate	64 Gbps (PCIe 4.0 x4); 32 Gbps on PCIe 3.0 x4 implementations	40 Gbps; 80 Gbps on USB4 Version 2.0
Usable PCIe bandwidth	Close to the full link rate, minimal overhead	Typically 22–32 Gbps after tunnelling overhead and shared allocation
Latency	Very low; behaves like an internal slot	Higher, due to packet encapsulation and routing
External GPU performance	Retains roughly 90–95% of native card performance	Typically 70–85%, with the largest losses at lower resolutions
Hot-plug support	Generally not supported; connect before powering on	Fully hot-pluggable, connect and disconnect freely
Power delivery	None over the cable; the dock requires its own supply	Up to 100 W, or 240 W with Extended Power Range
Display output	Not carried; data only	DisplayPort tunnelling drives external monitors directly
Device versatility	Narrow: eGPU docks and external NVMe enclosures	Broad: docking stations, displays, storage, hubs, all USB peripherals
Cabling	Thicker, keyed connector, practical lengths around 0.5–1 m	Slim reversible USB-C; passive to 0.8 m, longer with active cables
Driver requirements	Enumerates as a native PCIe device; no special software	Depends on host controller support; occasional platform quirks
Security	Raw DMA access; relies on physical control of the port	Device authorisation and IOMMU-based DMA protection
Availability	Specialist: mini PCs, handhelds and select laptops	Mainstream across modern laptops, mini PCs and desktops
Best suited to	A fixed desk setup where eGPU throughput is the priority	One-cable docking, portability and mixed peripheral use

👉 Click to learn more about How to add a GPU to a Mini PC?

Versatility and compatibility

There’s no doubt that USB 4.0 is the data transfer format with the highest compatibility. In this aspect, it surpasses OCuLink in everything. USB 4.0 can transfer video—something OCuLink cannot do—allows device charging—something OCuLink also cannot do—and can be used on any device with USB-C.

OCuLink is a standard that’s focused solely on data transfer and depends on a PCI port for its operation, so its presence in mobiles or tablets is practically non-existent, and it’s not the most common standard in laptops either. Its use is more localised to specific functions in specific devices.

Market availability

The vast majority of laptops and current mini PCs have USB 4.0 ports, and their use continues to spread more and more. It’s an almost universal standard, especially in PCs, and it’s even gradually being deployed in tablets and mobiles. By far, USB 4.0 is a much more widespread standard than OCuLink.

For its part, OCuLink is a much more niche connectivity standard, although it still has great acceptance. OCuLink is quite widely used in gaming PCs, portable consoles, and some mini PCs, especially when connecting peripherals such as storage devices or external graphics cards.

Which option to choose in 2026?

Now that you have a clearer idea of the main characteristics and use cases of USB 4.0 and OCuLink, it will be easier for you to choose between one or the other. The key here is the purpose for which you need your connectivity. Perhaps the most important thing to consider is the contrast between USB 4.0’s versatility and OCuLink’s stability.

When to Use OCuLink?

OCuLink excels in specific high-performance scenarios where maximum throughput is critical.

• External GPUs – Maximize graphics card performance
• High-speed storage – Peripheral storage devices
• Low latency – Minimal overhead for best performance
• Dedicated bandwidth – No protocol overhead

Best for: Professional gaming setups, video editing workstations, and high-performance computing tasks.

When to Use USB 4.0?

USB 4.0 is the versatile choice for most everyday connectivity needs and general use cases.

• Universal compatibility – Works with most devices
• Video transmission – Display connectivity support
• Power delivery – Charge devices up to 240W
• Data transfer – High-speed despite slight overhead

Best for: General computing, docking stations, multi-purpose connectivity, and everyday peripherals.

When to Use Both?

These standards are not mutually exclusive! A hybrid approach maximizes your device’s potential by leveraging the strengths of each connection type.

Use OCuLink for:

• External graphics cards (eGPU)
• Ultra-fast data peripherals
• Performance-critical connections

Use USB 4.0 for:

• Displays and monitors
• Charging and power delivery
• General peripherals and accessories

💡 Pro Tip: Many modern Mini PCs and workstations support both standards, giving you the best of both worlds!

Recommended Mini PCs with USB4 and OCuLink

At Geekom, you have an extensive catalogue of mini PCs that have both OCuLink and USB 4.0 ports to maximise your device’s potential. You now know their differences better and what each is used for, so let’s show you two ideal mini PCs for gaming and productivity, respectively:

GEEKOM MEGAMINI G1 Mini PC

(Note: This product is unavailable in the UK.)

If gaming is your thing, the ideal mini PC for you is the Mega Mini G1. It’s an absolute beast equipped with an Intel Core i9-13900H processor with 14 cores and 20 threads, with 32 GB DDR5 5200 MT/s expandable to 64 GB, and a solid NVIDIA GeForce RTX 4060 to offer you excellent graphics from the first minute. Additionally, it has an OCuLink PCIe 4.0 x4 port so you can connect an eGPU if you want to boost those graphics even more.

GEEKOM IT15 Mini PC

On the other hand, if you plan to use your mini PC mainly for productivity tasks with applications like Adobe Premiere or After Effects, then you’ll probably prefer the Geekom IT15. This mini PC comes in two variants, one with an Intel Core Ultra 9-285H with 16 cores and 22 threads, and another with the Ultra 5-225H with 14 cores and 18 threads. Its price range is between £729 and £979, much more affordable.

Conclusion

The differences between OCuLink and USB 4.0 are clear, as are their use cases. Thanks to its low latency and minimal overhead, OCuLink is the ideal protocol for connecting your eGPU and maximising your mini PC’s graphics capability. This also makes it excellent for connecting external SSDs, although it’s a less versatile protocol than USB 4.0, so it ceases to be the ideal option for other uses.

The greater versatility of USB 4.0 makes it an indispensable option for charging devices, transmitting video, and transferring data with USB or mobile devices, so it perfectly complements OCuLink. If you want to maximise your mini PC’s performance, it’s best to have both protocols and use them in their respective ideal use cases. With Geekom, you have excellent options to do so!