How are y'all benchmarking for temps?

I've just been using NVIDIA's overlay to get some temps on my 4090. Wondered what everyone else is using to get temps and power from their cards as they play games.

My overlay is showing about max 53°C-54°C while getting 140-145 FPS on 3840x1600 during RDR2 after 60 minutes. This is in a loop with a 360mm and 240mm radiator (and yes, cooling my CPU, which is a 65w TDP Ryzen 5800X). Power draw is only maxing around 300w too.

Seems off, so curious the tools you all use so I can try others to get a better idea