HP Spectre x360 15t is a convertible laptop that is on sale right now. It is one of the first HP laptops and ultrabooks to don a true 4K UHD display with full RGB panel. This has been confirmed by multiple users who had earlier pre-ordered this amazing ultrabook.
Today, they received the new HP Spectre x360 15t with Nvidia 940MX and they have confirmed that it does indeed have a real 4k display with non-pentile matrix display. For those who do not know, pentile 4k display was used in previous iteration of this laptop.
In fact, if you go to Start Menu > type "Device Manager" > Monitors > Generic PnP Monitor > Properties > Details > Hardware Ids and you will find this uses BOE06C3 which is a true RGB non-pentile 4k UHD laptop display and that makes it excellent for people who like sharp screens.
More and more laptop manufactures have started using true 4K display. Recently, Lenovo churned out Yoga 710 4k that has similar specifications and has 100 percent true UHD 4K display. There is no pen digitizer present though which is available in HP Spectre x350 15t.
The previous model of this very laptop used RGBW pentile matrix to cheat the people without actually providing full detail of the resolution. This new ultrabook makes use of completely different display and it looks like HP finally listened to the complaints of people and equipped the new HP Spectre x360 15t with true RGB non-pentile display for best possible clarity.