Jarrod’s Tech put together an interesting experiment that aims to test the limits of a Thunderbolt 4 laptop connector with an external GPU setup featuring Nvidia’s RTX 4090 FE card. Of course, no one expects an eGPU setup to perform on the same level as the desktop equivalent, but the test also reveals glaring limitations for Intel’s top-of-the-line i9-12900HX mobile CPU. Jarrod thought an i7-1260P laptop might be bottlenecked in some cases, so he added an i9-12900HX model in the mix for good measure. Surprisingly enough, the i7-12600P proved considerably faster in some gaming scenarios.
The tests first reveal that a desktop PC with PCIe 4.0 X16 connection has a 10x higher bandwidth compared to the Thunderbolt 4 laptops. This gap should soon be considerably reduced with the introduction of the 80 Gbps Thunderbolt connection, and things may further improve with the 120 Gbps mode, but until then, Thunderbolt 4 / USB4 does not seem to cut it for an RTX 4090.
As Jarrod presents the results of the first 10 gaming tests, it becomes clear that there is a problem with the Thunderbolt 4 connection on the i9-12900 HX, which is significantly lagging behind the i7-1260P in quite a few cases. Not to mention that the RTX 3070 Ti laptop GPU coupled by default with the i9 CPU proves to be faster than the RTX 4090 eGPU in 1080p and 1440p resolutions. Seeing the pattern forming, Jarrod skipped the i9 tests altogether for the remaining gaming scenarios
In some games, like Red Dead Redemption 2, the laptops showed the same FPS counts across all resolutions, implying some sort of bottleneck. Besides highlighting how limited the Thunderbolt 4 connection is when it comes to GPUs that can take advantage of large bandwidths, the tests also show the limits often translate to unbearable stuttering with 1% low FPS counts under 30.
It is suggested that the Thunderbolt 4 limited bandwidth could be caused by the resizeable BAR feature. However, Jarrod was not able to verify this as the laptops do not offer an option to disable it. The video comments also offer an explanation why the i9 is slower: apparently, the i7-1260P has the TB4 controller built into the die, while the i9-12900HX gets a Maple Ridge TB4 controller on the laptop motherboard.
Since we now have AMD laptops and mini PCs with USB4 connectors, maybe it would be nice to see how Team Red’s implementation fairs against the Intel one.
Buy the ASUS ZenBook 14X OLED laptop with Intel i7-1260P CPU on Amazon
I first stepped into the wondrous IT&C world when I was around seven years old. I was instantly fascinated by computerized graphics, whether they were from games or 3D applications like 3D Max. I’m also an avid reader of science fiction, an astrophysics aficionado, and a crypto geek. I started writing PC-related articles for Softpedia and a few blogs back in 2006. I joined the Notebookcheck team in the summer of 2017 and am currently a senior tech writer mostly covering processor, GPU, and laptop news.
.