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Asus Packs GeForce RTX 4090 Into Pricey New External GPU

The $1,999 ROG XG Mobile stands out for its portability, but the external GPU only works with Asus' Flow laptops since it requires the use of a proprietary connector.

 & Michael Kan Principal Reporter

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Asus is now selling a new external GPU for laptops that provides access to an Nvidia GeForce RTX 4090 for more graphics firepower. 

Asus' website lists a 2023 version of the ROG XG Mobile. But the add-on product will set you back $1,999—or $400 more than the starting price for the desktop-based RTX 4090 GPU.

Of course, the ROG XG Mobile stands out for its portability, and its ability to easily upgrade a laptop with more graphics processing. All you have to do is hook the ROG XG Mobile to the PC through a cable. The product itself weighs in at 2.86 pounds.

The ROG XG Mobile connected to a laptop.

But on the downside, the peripheral only works with six laptops in Asus’ Flow series, including 2022’s ROG Flow Z13. That’s because the external GPU functions over a proprietary PCIe connector exclusive to compatible Flow laptops. 

Another negative is how the product only features the laptop-focused RTX 4090, not the more powerful desktop version. So buyers are only getting 16GB of video memory and about half of the GPU processing cores found on the desktop-grade RTX 4090.

But on the plus side, the peripheral does offer a collection of ports, including an Ethernet port, an SD card reader, and several USB ports, along with HDMI 2.1 and DisplayPort 1.4. It also looks like the product can double as a power supply for an Asus laptop, since it features an integrated power adapter to connect to an electrical outlet.

The product represents a refresh of the 2021 ROG XG Mobile, which tapped a mobile-focused RTX 3080 GPU. Our review praised the earlier model for being compact and easy to use. But we were also turned off by its high price and disappointing gaming performance. Our tests showed the peripheral often lagged behind laptops with built-in RTX 3000 GPUs. So we’ll have to see if Asus was able to resolve the performance gap problem. Stay tuned for our review.

About Our Expert

Michael Kan

Michael Kan

Principal Reporter

My Experience

I've been a journalist for over 15 years. I got my start as a schools and cities reporter in Kansas City and joined PCMag in 2017, where I cover satellite internet services, cybersecurity, PC hardware, and more. I'm currently based in San Francisco, but previously spent over five years in China, covering the country's technology sector.

Since 2020, I've covered the launch and explosive growth of SpaceX's Starlink satellite internet service, writing 600+ stories on availability and feature launches, but also the regulatory battles over the expansion of satellite constellations, fights with rival providers like AST SpaceMobile and Amazon, and the effort to expand into satellite-based mobile service. I've combed through FCC filings for the latest news and driven to remote corners of California to test Starlink's cellular service.

I also cover cyber threats, from ransomware gangs to the emergence of AI-based malware. In 2024 and 2025, the FTC forced Avast to pay consumers $16.5 million for secretly harvesting and selling their personal information to third-party clients, as revealed in my joint investigation with Motherboard.

I also cover the PC graphics card market. Pandemic-era shortages led me to camp out in front of a Best Buy to get an RTX 3000. I'm now following how the AI-driven memory shortage is impacting the entire consumer electronics market. I'm always eager to learn more, so please jump in the comments with feedback and send me tips.

The Best Tech I've Had:

  • My first video game console: a Nintendo Famicom
  • I loved my Sega Saturn despite PlayStation's popularity.
  • The iPod Video I received as a gift in college
  • Xbox 360 FTW
  • The Galaxy Nexus was the first smartphone I was proud to own.
  • The PC desktop I built in 2013, which still works to this day.

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