MAG Z790 Tomahawk WiFi has an I226-V ethernet controller which likes to drop connection at random times and this issue did not have any workarounds the last time I checked (about 2-3 months ago). So be prepared to buy another ethernet controller. Just google "I226-V issues".
Unfortunately G.Skill memory sticks have issues with thermal pads. Not only do they not cover the power components on the PCB but some sticks have thernal pads that do not even contact some of the memory chips. Which results in these chips overheating during stress and eventual app/system crash. You can read about this here:
https://www.reddit.com/r/sffpc/comments/1470w7u/hot_ddr5_temperatures_probably_best_to_avoid/
Well it seems that the MSI has used I225-V for the MAG Z790 Tomahawk MAX WiFi.
https://www.alktech.co/articles/review-msi-mag-z790-tomahawk-max-wifi-lga1700-motherboard
But I225-V is not problem-free either.
https://forum-en.msi.com/index.php?threads/z790-tomahawk-wifi-max-ethernet-problem-need-urgent-help.390769/
However for PRO Z790-A (MAX) which also uses I225-V there seems to be a workaround (in OP post & at the bottom):
https://www.reddit.com/r/intel/comments/10fscft/intelr_ethernet_controller_3_i225v_only_reaching/
But this workaround may not work for everyone.
No idea. I've just seen reports about RIPJAWS S5 having thermal pads not contacting some memory chips. And also some posts here on reddit about Z5 high temps under stress (70-80C which is still within spec though).