Dear colleagues,
we are currently performing non-uniform refinement on a large volume (about 350 A in each direction), with a full box size of 550 cubed voxels; we have about 370 thousand particles extracted with 550 x 550 px (1.1 A per px).
After four or five cycles of refinement, as we approach a GSFSC resolution of 3.1 A, the following message appears repeatedly:
*[CPU: 50.68 GB] Optimizing FSC Mask… *
[CPU: 50.68 GB] Using full box size 550, downsampled box size 288, with low memory mode disabled.
[CPU: 50.68 GB] Computing FFTs on GPU.
[CPU: 51.92 GB] Using full box size 550, downsampled box size 288, with low memory mode disabled.
… (several more times)
[CPU: 51.92 GB] Using full box size 550, downsampled box size 288, with low memory mode disabled.
[CPU: 51.92 GB] Computing FFTs on GPU.
[CPU: 51.92 GB] Done in 150.816s
Then, NU-refinement consistently ends at around 3-ish A GSFSC, regardless of further significant improvements of earlier steps, from motion correction to CTF fit and so on.
Does this mean there that we are being limited by our hardware, thus preventing achieving higher resolution, or have we potentially reached the dataset limits?
Happy to provide further information.
I thank you all beforehand for your attention.