Using an RTX 4090 on OCuLink may seem crazy, but the enthusiast wanted to test how far the most powerful graphics card on the market can go in an optical interface originally developed for servers, but which has gained a following in the consumer market in recent months. when connecting external graphics, as it is the interface with the highest bandwidth available, surpassing Thunderbolt 4.

External graphics are a good solution for improving the graphics system of those personal computers that do not have an internal graphics chip with sufficient capacity. A great example of use is notebooks or Mini-PCs. Imagine having an ultraportable, excellent for mobility, but which only has an integrated graphics card in the CPU and no dedicated graphics card. A recent use case would be the new Lenovo ThinkBook 14 which has OCuLink support.

In this scenario an external graphics card is ideal when you are at the computer, connect it to your laptop and you can run advanced video games or professional applications with guarantees. With this, you would only need one universal device. And if you want a desktop-type configuration, you can connect additional peripherals, monitors, keyboards or mice

RTX 4090 via OCuLink

Although OCuLink is the fastest connector on the market 64 Gbps in bandwidth (exceeding 40 Gbps Thunderbolt 4) using an external graphics card will always have a performance loss compared to a desktop where we plug the card directly into a PCI-Express slot. But how much is lost? A Chinese website for tech enthusiasts put it to the test to find out. The results show OCuLink’s enormous potential for external graphics, as well as its challenges.

On a new generation laptop with an Intel Core Ultra 5 125H processor, they tested a RTX 4090 via OCuLink with one of the most widely used benchmarks in the industry, 3DMark. When using the laptop’s own display, there was a 23% performance drop in Time Spy and 5% in Time Spy Extreme compared to a desktop with an RTX 4090. However, when using an external display, the performance drop was reduced to 17% and 0%, respectively. , respectively

The media also tested other graphics such as RTX 4070 Ti and the results were pretty good. The loss was 10% with the laptop screen, but was practically negligible when using an external screen. The reason an external monitor improves performance is because it reduces the bandwidth load on the OCuLink. Scrolling images to the laptop’s internal display consumes bandwidth that could otherwise go to the GPU. With an external display, more bandwidth is available for the GPU to perform at or near its full potential.

Time Spy Extreme was also observed to have a lower performance impact than Time Spy, probably because its higher frame rate results in more GPU system communication per frame and this overloads the interface bandwidth. It means that lower resolutions or frame rates, OCuLink will perform better and performance losses compared to desktop will be very low.

This interface is very interesting for the mentioned cases, a notebook or Mini-PC whose graphics we want to improve. For example, when they use integrated graphics, something that most are. It must be said that it is not necessary to use the very expensive RTX 4090 to see the benefits and we could use other lower series. With Thunderbolt 5 on the horizon and its 80 Gbps bandwidth, the eGPU market may become more competitive.