Depending on what model of the HP EliteBook 840 G3 you have there are different CPU/GPU configurations. Drivers are on HP's website and there is an archive below essential oem drivers.
Basic Specs:
Screen Size: 14 inches
Max Screen Resolution: 1920x1080 pixels
Processor: 2.3 GHz Intel Core i5
RAM: 8 GB DDR4
Memory Speed: 2133 MHz
Hard Drive: 256 GB SSD
Graphics Coprocessor: Intel HD Graphics 520
Chipset Brand: Intel HD Graphics
Card Description: Integrated
Wireless Type: 802.11g/n
Number of USB 3.0 Ports: 4
Average Battery Life (in hours): 9 hours
