Earlier this year, we saw an eGPU box from Lenovo with a number of arguments in its favor. For those of you trying to remember what an eGPU is, it’s simply an external graphics card, generally used to boost the performance of a notebook PC when it’s in fixed use. A solution that several brands have been experimenting with for years. But Lenovo, with its ThinkBook TGX, may have found the right formula.
What is an eGPU, and does it really work?
The eGPU could considerably broaden the range of uses for a notebook PC, from gaming to graphics creation. However, it comes up against the problem of the decorrelation between graphics card throughput and that of available external connectors. Even if solutions are making progress on this last point (Intel’s Thunderbolt comes to mind), there’s still a real gap between the solutions actually available and the data rates of the latest graphics cards. To put it concretely, connecting a latest-generation graphics card to your laptop is possible and relatively easy today… But you’ll always have a more than significant gap between this same card in a fixed PC and when it’s used as an eGPU.
If we’re talking about Thunderbolt 4, in theory we’re talking about 40 Gbit/s bandwidth. Staying with theory, let’s consider that PCIe 5.0 16X has 63.015 Gbit/s. The gaps are narrowing, but they’re still there. Intel has announced Thunderbolt 5, which promises bandwidth of 80 Gbps, but it is not yet widespread. Lenovo has therefore used a different solution, called TGX, which can handle bandwidths of up to… 64 Gbit/s.
ThinkBook TGX: an exciting first step
The result is support for the latest generation GPUs, including an Nvidia GeForce RTX 4090, with no connection bottlenecks, and therefore no compromise on performance.
But there’s a catch, of course: the ThinkBook TGX is currently designed for just one Lenovo notebook – the Lenovo ThinkBook 14i Gen 6 , which is the only notebook with the TGX connector. This connector clearly seems to make use of OCuLink technology, but both are far from the standard that Thunderbolt is becoming.
So what is this OCuLink standard? It’s the PCI-SIG consortium’s desire to offer a standard wired protocol for PCIe peripherals outside the motherboard, in competition with Thunderbolt…and free of charge. A good idea, but probably too far behind, commercially speaking, the initiative taken by Intel with Thunderbolt.
We’re clearly impatient to see how all this evolves, as we’ve never been so close to being able to reproduce the performance of a “real” GPU used in a classic PC for a mobile solution. An approach that also opens up new prospects for mini-PCs and, why not, future alternative solutions to consoles.
Just for fun, here’s my 8-year-old “do-it-yourself” solution for connecting an external graphics card to an old laptop. You’ll easily see how far we’ve come.
