I'm planning a new system with an X870E motherboard, a Ryzen 9 9950X3D, 64GB of DDR5, and an RTX 5090 as the main graphics card. I also have an RTX 4060 Ti that I'd like to dedicate to PhysX, mainly for older games such as Borderlands 2, which uses 32-bit PhysX features that I initially thought were unsupported on the RTX 50 series. I'm considering connecting the 4060 Ti through an OCuLink or USB4 eGPU enclosure so the 5090 can run at full speed internally. Is it technically possible to use an external GPU this way as a dedicated PhysX processor, and would the performance be good enough in PhysX-heavy games? I'd also like the setup to remain useful if I later connect the eGPU to a laptop.
3 Answers
Before planning around the idea that the RTX 5090 cannot handle these effects, verify the latest NVIDIA driver and game patches. Some 50-series PhysX issues have reportedly been fixed, which may eliminate the need for a second card entirely. If Borderlands 2 still has problems, testing the 4060 Ti internally first would be a better baseline than buying an eGPU enclosure.
A dedicated external PhysX card is technically complicated and probably not worth the cost or latency. USB4 and similar connections have much less bandwidth than a direct PCIe slot, and PhysX has to move data between the main GPU, CPU, and secondary GPU. Even if the driver accepts the external card, performance may be inconsistent, especially in older games. Also, recent driver updates reportedly improved PhysX support on RTX 50-series cards, so check whether the current driver already runs the games you care about before buying an enclosure.
If the motherboard and drivers expose the external GPU as a normal secondary NVIDIA adapter, it might be detected, but USB4 is not equivalent to an internal PCIe slot. OCuLink can provide a better connection, yet it still adds an external link and enclosure overhead. A directly installed secondary card would be much more predictable, even if the slot runs at reduced lanes. For a handful of older PhysX games, the simplest solution may be to use CPU PhysX or adjust the game’s PhysX setting rather than build a dedicated external setup.
This system will use AMD with USB4 rather than Intel Thunderbolt. I’m mainly revisiting older games, so compatibility matters more to me than gaining extra performance in modern titles.
The main game I’m concerned about is Borderlands 2 because of its 32-bit PhysX effects. I was hoping to keep the 4060 Ti available without taking lanes away from the 5090.