Is you DDR4 dual rank with good timings like the ony I posted CL16-16-16 or garbage timings like CL16-20-20 and sinlge rank?With rt ultra my gpu usage is 100%. dlss off.
You try with dlss on on or off ?
But on second platform you have ddr4 3600.I have to 3600 ddr4.
I have 100% usage when using RT ULTRA but DLSS must be off.
I'm using dual rank Samsung B-Die which out of the box will outperform other DDR4 single rank kits by 10-20% in CPU limited games and I can easly push it to 4000MT/s with CL16.
With RT enabled you will become CPU limited not GPU limited and this is as expected on RTX 3090 Ti especially when you will use DLSS which will render game at lower resolution and then reconstruct the image.