Just a side'ish-note: if you did not actually use the new device for long, it's quite possible it was never good.

I would hope things to shut down automagically before overheating too much. Excessive use of voltages higher than the thing can take, however, include a greater risk (in my opinion) of permanently damaging anything.

But yeah, if you did not try FFXI with it before, I might suggest doing some more testing with it before deciding the final outcome. Perhaps under-clocking it, so as to see if the problems arise even when the device is using clocks below its defaults. If it had any warranty left still with it, it's of course likely to be void now (for most retailers).

Something else I thought of is that, is your FFXI really okay otherwise? What you described seems rather funky to come from mere GPU's doing. Makes me think of some evil third-party software's doing, but I can also easily imagine it being possible to pull that off with over-clocking alone. I've personally witnessed some quite interesting results, but not quite anything what you described. ^^

Whenever over-clocking something, it should be indeed done in small increments, as you might have discovered now...


As a final note, even if Windows recognises your device without you installing any software, it does not mean you should use the drivers it installs for it. I'd definitely suggest on procuring them from whoever manufactured it instead (goes for any device, really).