That is correct. Also the things you want to use as handles are either plastic or large metal pieces like heatsinks. Hold boards by the edges as there is usually an earth (ground) track around there, and cards by the metal tab. This way you avoid contact with any part that leads to earth through componentry which avoids damage. It also saves you from harm. Provided, however, you don't poke inside the power supply case there is actually no danger to you within the computer (FWIW), but it is wrong to think that way.