Would the +100W TDP (450W) affect mining efficiency or can the power limit probably just be tuned down more than now without a significant loss?
Are you asking about the RTX 3090 graphics card?
The optimal solution for mining this video card is 114-120 megahash with a consumption of about 300 watts.
You will not be very successful if you add the power limit.
This will only lead to additional overheating of the video card.
Yep proper 3090 set 275 to 305 watts get 110-116 megahash
Mine are at 285 watts and 112-113 hashrate.
as for what will the 3090ti do? hmmm
1080 vs 1080ti was 38 to 51. that is 1.34 better so 1.34 x 112 = 150 max as my guess