If it passes RB, have no reason to go any further. If there are failures, at that point we would try and narrow them down:
a) If a memory error appeared likely, I'd test w/ memtest 86+ overnight (12 hours0.
http://www.memtest.org/
b) Never used on a new system but if had storage concerns, would use manufacturer supplied SeaTools by Seagate of whatever is appropriate for other manufacturers.. We haven't used a HD in about 7 years (only SSDs and SSHDs)
http://www.seagate.com/files/www-content/support-content/downloads/seatools/_shared/downloads/pdf/SeaTools-for-windows-en-us.pdf
If you want to go further, there's SpinRite which is the best tool available... Crystal Disk is another option.
https://www.grc.com/sr/spinrite.htm
c) Again, there's numerous CPU stability testing tools but they don't give me any answers that RB doesn't. You could use Intel's own tool but to my eyes, doesn't provide anything of value.
https://downloadcenter.intel.com/download/19792/Intel-Processor-Diagnostic-Tool
d) Motherboard diagnostics are built in, the MoBo checks everything at start up, and if you chose wisely, the MoBo is equipped with an lCD that will display a 2 character code that points to the problem area.
e) For GPUs I test with Furmark to determine if cooling is adequate and card is not throttling
If you just want to buy something. AIDA 64 will give you loads of data, but most of that is readily available and freely available. It's $200 for a single tech license
https://www.aida64.com/products/aida64-engineer
Other purchase options:
https://www.aida64.com/online-store
We've been building CAD Workstations for going on 25 years and have not had the need or saw any value to using anything other than the aforementioned tools.