80 PLUS vs Non 80 PLUS means, the 80 PLUS one is more efficient.
According to the specs where it has two +12V rail and 18A each it will still support the GTX 465 fine, but it will not be staying long really. You should I think replace it next time, but temporally should be fine.
EDIT: I Forget about connectors, you should get an adapter.
by not long how much do u mean ??