How much damage ... hmm ... ruined GPU(s), MOBO, RAM, CPU or anything it's (PSU) attached to or powering.
IMO - most PSU's and components, exceptions sure, have 3 year warranties and often PSU's come with a 5 year warranty. Contact the OEM manufacturer for an 'RMA' request (exchange). If it's a need to know now then go to the local store (e.g. Best Buy see if there's an 'Open Box', bring it to your (dorm) and try it. If it corrects the problem then you'll know and can either return the Open Box and RMA the bad PSU or keep it.
From what you've described it 'seems' to be the PSU, it could be the MOBO. Again, WARRANTIES