if anybody still paying attention to this thread...
if z690i mobo is like z790i, as mentioned need to make sure pad is making contact with nvme. also, need to make sure you screw down the heatsink correctly. on my mobo, the screw is to hold down m2_2 and there is no screw for the m2_1. you actually screw the top heatsink screw into that screw. if you use the m2_2 screw to hold down m2_1 it will be janky as f and won't make contact at all.
another trick is go to bios and look for PCH voltage. it should be .820V. you can UV as low as .600V but it might not be stable. try .650-.700V. I have been using @ .650V for a few months. it brought down PCH temps ~4-5c.
one more trick. if you have a nvme on the back of mobo get a 3mm heatsink (or 1mm copper) and attach using EPDM band. epdm is a synthetic rubber band and lasts a long time. it also won't dry out and snap like the cheap rubber bands you get buying cheap thermal pads specifically for nvme. cut one epdm in half if all you have are thick ones. I did this in a sff case, the a4 h2o, and I forget but it brought my temps down out of 60s to mid 50s. I was very happy because now it was maxing out where it used to be idling. but wait, there's more depending on case you have. in my case, haha, the 3mm heatsink was touching the riser as evidenced by the little grooves. I did some mods with my case like using PET plastic to wall off gap above gpu and cpu heatsink. I basically cut off all airflow, even taped the bottom vent holes so only way air get in is below cpu heatsink and below gpu. this gave my 2 case more negative and thus more airflow. my back nvme temps now idle mid 40s and peak @ 55c. m2_1 dropped ~5c. PCH also dropped another 5c. MOS and my gpu temps across the board went down 2c.
