I haven’t quantized these myself since TheBloke has been the main provider for all the quantized models. But when I did a 8 bit quantization to see how it compares to the transformers library load_in_8bit 4 months ago(?), it didn’t use my GPU but loaded each shard into the RAM during the conversion. I had an old 4C/8T CPU and the conversion took like 30 mins for a 13B.
I can quantize models up to 70B just fine with around 40-50 GB of system RAM, using the GGMLv3 format.
GGUF seems not optimised yet, since quantizing with a newer version of llama.cpp supporting the format fails on the same hardware. I expect that to be fixed shortly.
For inference, I understand that the hardware requirements will be identical as before.