Qualcomm's Snapdragon X Elite laptops have a dirty secret when it comes to external monitor support
The first wave of Snapdragon X series laptops have been relatively well received so far, software incompatibilities aside. Incidentally, Qualcomm is now rumoured to be working on second-generation Snapdragon X Elite chipsets, early details of which we have covered separately. However, it seems that the company's first-generation Snapdragon X chipsets are not working as advertised for many when it comes to external monitor support.
For instance, Microsoft insists that its Surface Laptop 7 and Surface Pro 11 (curr. $1,099.99 on Amazon) machines support 'DisplayPort 1.4a' through their USB Type-C ports. In summary, DisplayPort 1.4a has a 32.40 Gbit/s theoretical peak bandwidth with an HBR3 mainlink (8.10 Gbit/s per lane). Thus, the Surface Laptop 7 and Surface Pro 11 should be capable of outputting to a 4K monitor at 120 Hz or an 8K one at 30 Hz.
The same should true of other Snapdragon X series laptops too like the Yoga Slim 7x and XPS 13 9345, which Lenovo and Dell advertise as featuring 40 Gbps USB Type-C ports, respectively. For reference, Lenovo and Dell refer to their laptops as supporting DisplayPort 1.4 not DisplayPort 1.4a. Both standards should have enough bandwidth to reach 4K/120 Hz or 8K/30 Hz when connected to an external monitor, though. Qualcomm reinforces this too, by claiming that the Snapdragon X series supports DisplayPort 1.4 with:
3 displays up to 4K @ 60Hz HDR10, 1 display up to 5K 60Hz, or up to 4K @ 120Hz (5K, 4K, 4K in concurrency)
Confusingly, Qualcomm also reports in its Snapdragon X series overview that while its latest chipsets offer 4K/120 Hz support as a 'maximum on-device display resolution', 'maximum external display resolution' drops to 4K/60 Hz. In short, this is DisplayPort 1.4. In fact, a 4K/60 Hz maximum external display resolution tallies with DisplayPort 1.2, which has a 21.60 Gbit/s peak bandwidth.
Understandably, early adopters of Snapdragon X series laptops have been left perplexed by what their machines should support. Allegedly, one Redditor has been able to activate a 120 Hz refresh rate on their 4K monitor by disabling Display Stream Compression (DSC). Anecdotally, we have had no such luck with that solution on any Snapdragon X series machine. Instead, our Surface Laptop 7, Surface Pro 11, Yoga Slim 7x and XPS 13 9345 units all peak at 4K/60 Hz or 1440p/120 Hz regardless of the USB Type-C port or cable used.
Please note that we tested these devices with MSI's MPG 321URX QD-OLED monitor, which is listed as having a DisplayPort 1.4a port and has no trouble outputting at 4K and 120 Hz or higher on AMD, Intel and Apple M-based devices. Ultimately, it seems that external monitor support on Snapdragon X series monitors is not working as advertised for now. Unfortunately, it remains to be seen whether it is by design or the result of faulty Adreno drivers.
