Okay, good question to which only an electrician who's into frying equipment would be able to answer with examples. The most basic problem is that no 180W PSU has PCI connections to plug in your graphics card. But, if you were to use adapters from the molex cable, I would suspect that you would either set the PSU on fire or it would protect itself (and you) by shutting down - no restarting. If the PSU does not out and out die from the first event (it will soon), you might have to wait a few minutes for it to reset itself before trying again (with the same expected result).
i only want to know that what it will generally do to the psu or the pc.