Try to underclock Radeon GPU, but pp_od_clk_voltage is MISSING?

I did look around the Arch Wiki, but somehow missed that section. Thank you. It seems I may have been operating on my integrated GPU, not my RX 7600. I think the integrated graphics are card0, and the discrete graphics are card1. But here’s a mystery: /sys/class/drm/card1/device/ DOES NOT CONTAIN pp_od_clk_voltage

?!?!

Clearly I’m not understanding something.