Why is Windows reserving half of my 12 GB of RAM?

The hardware details are more concerning than the reserved-memory number. An i7-9850H should show 6 cores and 12 threads, and it should not be identified with Intel HD Graphics 500. “Four 3 GB modules” is also an unusual report. This could be incorrect SMBIOS data, a virtualized environment, corrupted or modified system information, or a problem with the motherboard firmware. Verify the CPU, memory, and graphics information directly in BIOS/UEFI and with a trusted hardware-information utility.

A BIOS or UEFI setting may be reserving a large amount of system memory for the integrated GPU. Look for options such as UMA Frame Buffer Size, iGPU memory, DVMT pre-allocated memory, or shared graphics memory, and reduce it to a normal value such as 128 MB or 256 MB if the system allows it. Also check whether the firmware detects the full amount of RAM before changing anything in Windows.

The reported memory speed and graphics model do not match the listed processor. DDR4-2666 is typical for that CPU, while 1600 MHz is more associated with older DDR3 systems, which are not compatible with a 9th-generation mobile i7. Before adjusting Windows settings, confirm the exact computer model and inspect the BIOS version and hardware summary. If those values are wrong there too, update or recover the manufacturer’s firmware rather than relying on the Windows display.

If the firmware itself does not show the expected hardware, shut the computer down and reseat the memory. Try one module at a time in the recommended slot, then test the other modules and slots. A poorly seated or failing module can sometimes result in a large hardware-reserved region even when Windows still boots. If the machine is a laptop, make sure the memory configuration is compatible with its specific motherboard.