You might have the n_samples (aka batch size) set to a number greater than 1? That basically multiplies the amount of VRAM you’re using.

I can generate a 512x512 on my 10gb 3080 no problem (or three 384x384 at a time)

Try the hlky fork: https://github.com/hlky/stable-diffusion

It measures memory usage as well.

Perhaps a different kind of chipset that isn’t optimized yet? Just a guess based on other graphics processes.