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The biggest risk may be the possibility of frying the motherboard via electric shock, secondly might be messing it up with liquids. In third place, I'm thinking dust. I've never cleaned my 5 year old laptop here. But in the future, I'm thinking of being more cautious. I did use a regular vacuum on a desktop.

Yeah being an open case it's something I need to be more careful around. Though by using old parts I dont really care if it fries or gets dusty. If it was not for this project I would have scrapped them.