Why is the Nanite VRAM Cache hardcoded to NVIDIA 2GB vs AMD 4GB?

Salcoj
Wed, 08 Oct 2025 15:02:50 +0000
Rendering

Hi!

I recently fought with high VRAM usage. Weirdly, my nvidia PC uses 6GB VRAM while the AMD PC uses 8GB. While investigating using the resource viewer tool, I got interested in the Nanite ClusterPageData buffer. I couldn’t reduce it by CVAR so I took a look into the engine code.

UE allocates 4GB by default on AMD cards instead of 2GB everywhere else.

Now I am just wondering. Why is this hardcoded and why do AMD cards get 2GB VRAM per default more?
Not saying that this is wrong. But I would like to gain insight to the reasoning for this.

NaniteStreamingManager.cpp on UE5.6:

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