Same issue, occurs for me mostly when roaming around a big scene on UE4.25, UE4.26 and UE5.0.
I tested ALL what is listed above, one by one and nothing worked.
What worked for me :
Lowering the clock speed of both the GPU and GPU Memory Clock (VRAM) by 100mhz and 200mhz respectively, via MSI afterburner as follows.
Specs :
- GTX 1080
- i7-6700K
- Windows 10 Version 21H1