The tensor cores are eating up all the power.
Definitely on the right track. Turns out it's a combination of DLSS and MFG. Frame limits were actually detrimental and often inaccurate for what they were supposed to be: 75 FPS showed at 60 via MS AB, and 60 could be 50, and anything less than 144 introduced stuttering. Never really seen a game behave this way before, in terms of added stuttering while not affecting power usage along with these lower-than-FPS limits. Just plain weird, so ultimately I just left them uncapped.
Oh well, the good news is that I just toggled a few things and eventually managed to lower power usage to comfortable levels. Here's another oddity: MFG above 1x instantly spiked power usage. DLSS above balanced: the same.
Here's a breakdown (these are based on running through Beuclair and off the top of my head after some quick experimenting, so should be considered more of a ballpark approximation):
DLSS Balanced +MFGx1 + Path Tracing on = 275-330W / 75-130FPS
DLSS Balanced +MFGx1 + Path Tracing off = 225-300W / 90-150FPS
DLSS Quality +MFGx1 + Path Tacing on = 320-350W / 50-90 FPS
DLSS Quality +MFGx1 + Path Tracing off = didn't try, but based on the above we could make a good guess on what to expect
The short end of it is that anything above MFGx1, or trying DLAA, will result in insane power usage. My recommendation is DLSS Balanced + MFGx1, and to each their own regarding path tracing. These settings, combined with power limits on a 5090, can once again tame it to around 250-350W levels while maxing all other game settings.
As far as image quality goes DLAA or DLSS Quality are very close to each other. DLSS Balanced is a noticeable decrease but still looks great imho, while performance doesn't look awful but is more of a compromise.
I've already got the better of 1000 Hrs with this game, and have used Halk Hogan's packs since around 2017, and they worked with CDPR for this remaster as well as the previous next-gen, so I'm not doing another playthrough now but will when the DLC launches next year.