The only hardware diagnostics I've ever used are
Hard drive testers.
Both have excellent free versions, the hard drive usually from the manufacturers site (eg Seatools from Seagate).
Otherwise system hardware issues are best dealt with by substitution. There are PSU checkers - but they don't tell the whole story - more of a go-nogo check.
I've been troubleshooting PCs since there were PCs and never purchased or felt the need for diagnostics like Microscope.
For what purpose are you looking?