Simonta,
As glad rag says.....
Are you powering up the caps separately? OR the whole unit??
If the former.... then as the old saying goes .... "If you have to ask how to do something potentially risky, it's not something you should be considering doing" (or a saying along those lines anyway !).
If the whole unit, e.g. a whole computer.... then who cares.... power it on and see what happens (all chassis casing etc. safely in place obviously !) You'll waste more time trying to figure out how to test capacitors safely.
All my own opinion... caveat emptor... follow any suggestions at your peril !