I've seen 7.1GB of RAM usage on my system, but that includes everything and not just the Witcher 3.. This mirrors what other tech websites have experienced as well.
been looking for an easier way to explain this. may write up a faq for various issues some day, prob not. meh :\
also, those sites are probably listing just the ram usage, maybe not pagefile/cache, and just for witcher3.exe.
decided to dust off 'sysinternals process explorer' for this example. observe cache is hitting 8gb. in this example, when commit+cache reaches 20-24gb (in my other tests, where pagefile was hitting 8gb), you're basically using all 16gb as commit (+some cache), some pagefile commit (mostly null/zeroed pages), and rest of 8gb cache, where? nowhere. that's why i consider 16gb an 'iffy' boundary, where it's best to have 8-16gb pagefile anyways. it most likely will be rarely used anyways (a 'page fault' is not pagefile usage, its mostly ram page usage, a 'hard page fault' is a disk read/write via pagefile)
something interesting here as well, digging up blogs that maybe i can link to explain it (although it's very technical):
http://brandonlive.com/2010/02/21/measuring-memory-usage-in-windows-7/
according to this, the committed pages in the pagefile are most likely empty... they're simply committed, but not used. zero'd out pages on disk, so it can address more ram instantly without having to commit unused bytes to ram (no sense in filling ram with zeros basically). this doesn't mean it writes them to disk to address that ram, it just copies the zeroed out pages in the virtual address space to ram, instant addressable memory.
for most practical applications, no pagefile will actually hinder performance in that scenario (16gb). unless it's very light usage (no anti-v, indexing/windows updates disabled, no browsers/comms, etc...)
essentially, current gen games/apps/windows require about 24gb+ addressable memory to operate efficiently (can vary from 20-32gb+ though). although making pagefile too small isn't good either, since then it'll be needing to drop/swap pages out for new ones constantly. must have enough breathing room (so i still lean towards 24-32gb+).
another way of looking at it is (using example above): peak commit 10.5gb, system cache 1.5gb = 12gb, that leaves 4gb for extra commits or remaining cache. over a few days, that # will decrease, leaving you with 0gb for extra commits/cache (technically you want at least 20% cache relative to ram volume, +extra for commits and to reduce memory management).
