I'm fairly sure 580W is enough for either card but it lacks 6 pin connectors. When i popped the pc case open i noticed it uses an adapter that converts two 4 pin cables to a 6 pin, thus powering my current gpu. Now if i had more than one free 4 pin cable remaining, i'd consider using another adapter and improvising something but seeing as there's only the one, well I'm in a bit of a pickle.
So my question is, do I need to aquire a new PSU to handle the two graphic cards mentioned? Because that would really suck
Well either of those two GPUs need max 500 Watts to run so wattage wise you are pretty above the maximum limit. But that PSU of yours isn't a good one.. It has no 80+ certification so, I'd advise you to change it sooner or later.. Its not wise to have cheap PSUs.