That I do not know, it was checked by the retailer who sold it to me - I sent it to them via mail.
But if my description of symptoms strongly suggest to you that the cause is indeed a melted PSU, that is probably the best bet I have - and getting a new PSU isn't that costly. I might even be able to borrow one.
The thing to bear in mind is, you have a PSU that was specified for a machine that had a graphic card that uses less
than 75w and it still had a bit of safety head room, not a lot but enough to get past the bean counters, you have then replaced that card with one that requires nearly 150w
and still expect to have enough power to run the rest of the system.