Leaderboard

DVMT must indeed be set to 64MB minimum to be able to obtain 4K output. 4K cannot be achieved with DVMT set to 32MB. See our published article on the matter: https://osxlatitude.com/forums/topic/17804-dvmtstolenmemfbmemcursormem-why-do-we-patch-these-for-broadwell-and-later There's normally no need to set DVMT to more than 64MB/96MB.

May be 4K display would require that "DVMT Pre-Allocated" set to 64MB? This could be done with 5400/5490. It requires an extracted version of the DELL BIOS to identify the location of the variable that controls "DVMT Pre-Allocated" setting. Update (Mar 5): I've identified the location of the following parameters for 7400 BIOS (V1.24, same in V1.23). You can modify them using modGRUBShell.efi. Here are the commands: 1. Disable "CFG LOCK": VarOffset = 0x6ED, VarStore: 0x1 (Name: Setup) Command for modGRUBShell.efi: setup_var_cv Setup 0x6ED 0x1 0x0 2. Set "DVMT Pre-Allocate" to 64MB: VaOffset = 0xA10, VarStore: 0x1 (Name: Setup) Command for modGRUBShell.efi: setup_var_cv Setup 0xA10 0x1 0x2 3. Set "DVMT Total Gfx Mem = Max": VarOffset = 0xA11 VarStore: 0x1 (Name: Setup) Command for modGRUBShell.efi: setup_var_cv Setup 0xA11 0x1 0x3 @Jazzoo Please give it a try.