Total noob wanting to buy premodded pstwo

just wondering, the store offers a 90day warranty. If the system does decide to break down in its lifetime, woudl it break down within 90days (if the install/chip is crap) or would it break down over time.

in other words, how safe would i buy with no warranty after 90 days.

It usually break down overtime. But this is totally random, no one can tell.

the damage the mod may cause, is it repairable/replaceable? what kind of damage does it cost to repair? laser damage or overheated motherboard problems??