Bluemoon_9 :
Chance is almost nil if you get a decent PSU. They have in built protection circuits, that prevents any harm to the computer components.
Twice I had a situation while building systems for friends where the new PSU is lemon(One CM, one Corsair), but in both cases nothing else is hurt.
This is a comment made by a Corsair AX860 PSU from Newegg:
1 out of 5 eggsBUYER BEWARE
This review is from: CORSAIR AX series AX860 860W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS PLATINUM Certified Full Modular Active PFC Power Supply New 4th Gen CPU Certified Haswell Ready
Pros: I bought this power supply for a really high components. Spent over $2800 in parts. Hooked up every thing turn on the computer and blow the components. The whole room had smoke. Called corsair and did a damage claim. The guy i spoke to on the phone said it would only take 3 day turn around but after 2 weeks they just got back to me saying that after their testing they found out it was a damaged power supply.
They only want to give me very little money for all the damaged parts. They said it was not replacement value but only depreciation value. I explained to them they are all brand new parts. They said if you buy a brand new car as soon as you drive off the lot you cant sell it for that price. I couldn't believe they would say something like that after their unit damaged my brand new parts. I am still dealing with the damage claim i will update my review after.
Cons: BUYER BEWARE
Other Thoughts: BUYER BEWARE