Most powerful laptops

The most powerful 15" laptop is Lenovo ThinkPad P53. It has Nvidia Quadro RTX 5000 graphics card. Maximum resolution of external monitor is 5K@60Hz. The most powerful 17" laptops are Dell Precision 17 7730 and HP ZBook 17 G5. Both laptops have Nvidia Quadro P5200 graphics card. Maximum resolution of external monitor connected to Dell Precision 17 7730 is 8K@60Hz. Maximum resolution of external monitor connected to HP ZBook 17 G5 is 5K@60Hz.

ThinkPad P53 specifications: http://psref.lenovo.com/syspool/Sys/PDF/ThinkPad/ThinkPad%20P53/ThinkPad_P53_Platform_Specifications.pdf

Dell Precision 17 7730 specifications: https://topics-cdn.dell.com/pdf/precision-17-7730-laptop_specifications2_en-us.pdf

HP ZBook 17 G5 specifications: https://h20195.www2.hp.com/v2/GetPDF.aspx/4aa7-2970eee.pdf