try do a clean install of Windows on the hdd for the 790 of concern.  you replaced MB but you may be using the same hdd with same OS that may have issue.

Replace/test size 2032 CMOS battery.  Bad batteries can cause boot problems and can often be the place to start.

If still no luck, try going into F12 Boot & Diagnostics menu and run Diagnostics.

Hi @redxps630 -- It sounds like the 790's are on Win7.  Nearly impossible to get fully working again without updates.  Also, Google will end Chrome support on Windows 7 and 8.1 in early 2023