i have found a cheap cx600m and was looking at reviews.
were they really that bad? people seem to hate them
also why were they bad?
Ancient design, low-quality capacitors. It wasn't in the pure garbage tier, but it was a mediocre-at-best PSU. They haven't made that old series in a *long* time so if it's used, that's a hard no. The only PSUs you should even consider used are ones that were very high quality to begin with.