For many years， external graphics card enclosures have been available， but their performance has always been limited by transmission bandwidth. Now， with the growing popularity of OCuLink and the emergence of Thunderbolt 5， a glimmer of hope has appeared.
So， which one is superior?
Let’s first briefly introduce OCuLink. Its full name is Optical Copper Link， a small PCIe interface standard developed by PCI-SIG. The host interface form is SFF-8611， and the device interface form is SFF-8612.
It supports native PCIe lane transmission protocols， directly and losslessly converting internal PCIe lanes into external interfaces. It offers advantages such as ultra-low latency， high bandwidth (64Gbps)， and high stability.
This technology was initially aimed at servers and workstations， but it has now become popular in external graphics cards and mini-PCs.
Thunderbolt 5 needs little introduction; it supports PCIe 4.0 x4， also boasting a bandwidth of 64Gbps， double that of Thunderbolt 3/4. It also supports the USB-C interface form， power delivery， and the connection of multiple displays and peripherals.
Thunderbolt 5 has been released for two years， but devices are still scarce and expensive. External graphics card solutions are beginning to adopt it.
Foreign media conducted tests using a Peladn Link S-3 external graphics card dock with an RTX 5070 Ti graphics card. The Thunderbolt 5 platform consisted of an ASUS ProArt Z890 motherboard and a Core Ultra 7 265K processor.
The tests revealed that while both Thunderbolt 5 and OCuLink share the same theoretical bandwidth， Thunderbolt 5 requires controllers at both ends， leading to increased overhead and performance loss. Consequently， its actual usable bandwidth is significantly lower. In all gaming tests， Thunderbolt 5 lagged behind， affecting both average frame rates and 1% low frame rates.
Of course， OCuLink is not entirely flawless either. It still faces issues such as performance loss， data cable compatibility， and a lack of hot-plug support. However， it currently outperforms Thunderbolt 5.
