I just ordered a 670 today, lol (EVGA FTW). I really don't know why that would happen. An i5 shouldn't even be close to being a bottlekneck for this card. The RAM could be a bottlekneck in the sense that 8 gb is recommended for gaming, but I highly doubt this to be the issue.
Is that the Power Edition or the Reference design card? Tom's did post an article regarding the stock voltages being tampered with by MSI, but those cards should have been phased out by now.
To be completely honest, I have no idea what your problem could be. Sorry