I turned off GPU shared memory in BIOS and my PC finally felt like 16GB again

It's nice to have tons of customization options as a PC owner, but the lack of plug-and-play simplicity is too big an inconvenience to ignore. Most of the time, your PC's initial setup holds it back from reaching its full potential, and you have to dig deep into your system's settings to unlock the true performance.

One instance of this regard is your PC not being able to fully access its RAM. Now, I'm not referring to the RAM speeds; the frequency limitation has become a well-covered topic in the community. I'm talking about your system reserving RAM for your GPU's memory pool, which can make your system quite sluggish.

Wait, where did my RAM go?

Task Manager told me I had less RAM than I paid for

The ceiling for RAM requirements is rising each day, as Windows 11 becomes increasingly demanding as an OS, driven by the growing need for background processes and AI features. I got 2x8GB of DDR5 memory for my system, thinking it was enough until it wasn't. When I opened Task Manager, I was shocked to see that only 12.9GB of the total RAM was accessible, which really pushed me to investigate the cause. Now, after some research, I found that your system's RAM is being reserved for your iGPU.

Your system reserves RAM for your iGPU even with a discrete GPU

The iGPU (integrated graphics card) in your CPU doesn't actually have VRAM. Instead, it relies on your system RAM as its video memory. Now, you might think that this won't be an issue for you since you use a discrete GPU, but your system still reserves a portion of your RAM for your iGPU, regardless. Most PC owners rarely access their system BIOS, which is why they're unaware of this fact.

Fortunately, you can free up the reserved RAM for your iGPU. Now, you can go 2 ways — either reduce the reservation to the lowest setting or disable your iGPU completely. To reduce GPU shared memory, follow these steps:

1. Enter BIOS by pressing Delete/F2.
2. Go to Advanced/Chipset Configuration/Graphics Configuration.
3. You'll either see DVMT Pre-Allocated/UMA Frame Buffer Size, depending on your CPU.
4. Clicking that option will allow you to change the system-reserved RAM for your iGPU — change to the lowest available setting.

To disable the iGPU completely, here's what you will need to do:

1. Enter BIOS by pressing Delete/F2.
2. Go to Advanced/Chipset Configuration/Graphics Configuration.
3. Set Primary GPU to PCIe, or if you can see an option for integrated graphics, disable it.

Disabling the iGPU completely means your PC won't display without your discrete GPU. Generally, I recommend keeping the system's reserved RAM for your iGPU at a lower value in case you need to boot without your discrete video card.

Other reasons your RAM shows less than full capacity

Unfortunately, not all missing memory is recoverable

Now, the iGPU has some reserved memory that can be changed or disabled, but your discrete GPU maintains a shared memory pool drawn from the system RAM, allocated by the GPU driver at startup. During heavy workloads or while running demanding video game titles, your video card can access this shared memory pool when the VRAM is under stress.

Unfortunately, there's not much you can do to change this, so you may have to choose your system settings wisely when running a video game, or just avoid burdening your GPU too much when performing any resource-intensive activity.

Even with the GPU's memory reservation, your RAM utilization might still be lower than the total capacity because some of it is set aside for other hardware, such as USB devices, memory-mapped I/O, driver overhead, etc. Unfortunately, nothing can be done to free up this RAM, as it is essential for complete functionality.

I freed up performance — here's what changed for me

As I've mentioned before, 16GB has become the bare minimum for Windows 11, and every megabyte matters to me because this memory is split among running the OS itself, third-party apps, and sometimes video games. I completely disabled my iGPU and freed up a gigabyte of RAM — although results may vary depending on the pre-allocated memory in your BIOS and CPU. Generally, you can free 32MB to 2GB of RAM, depending on the configuration.

For someone with an 8GB or 16GB RAM setup, this fix is really helpful. Memory is already pretty expensive, so it's important to make the most of it. Any additional measures you can take to free up more RAM include debloating Windows by disabling services you won't need. Additionally, Microsoft's RAMMAP also helps purge cached memory to improve performance.