Both are great cards the Gtx 680 lightning is locked now.There is a way to unlock it with a bios flash but is it worth the trouble.I don't know only you can decide that.
As for overclocking we know its a lottery, but I would imagine
you'd stand a better chance with a card like this than a vanilla one.
I would go for AMD's HD 7970 and its more powerful brother HD 7970 GHz Edition have been on the market for a while now. MSI has also launched their HD 7970 Lightning in June. Now ASUS has released the HD 7970 Matrix - a card that will directly compete with MSI's HD 7970 Lightning.ASUS has increased clock speeds to 1100 MHz. That is 50 MHz more than the GHz Edition and higher than any other HD 7970 card, including the MSI Lightning. Memory clock is, with 1650 MHz, also higher than any other AMD card. When [H]ard|OCP put the 20-phase Super Alloy Power technology and chokes to the test they hit 1310MHz on the GPU and pushed the memory to 7GHz, far beyond what any other HD 7970 they've reviewed could manage. That overclock was definitely noticeable when they benchmarked the card, which helped it win a Gold Award as the best HD 7970 they've seen ...
The card comes with a powerful triple slot cooling solution and adds many features for hardcore overclockers like support for VGA Hotwire, voltage control, and three buttons for direct GPU voltage control. You will also find voltage measuring points and a Turbo-fan button to set fan speed to 100% on the card.
Price-wise, the HD 7970 Matrix comes at $480, which is quite a price increase given AMD's recent price drops for the HD 7970. Here are professional reviews of the card w/benchmarks if your interested:
Hi, thanks for the replys. The matrix one looks great unfortunately I want a lightning to match my colour scheme mpower board etc.
I can get the 7970 lightning for about £40 cheaper then the 680 lightning so I am guesing I may aswell go which ever one is cheaper, now that nvidea has put a voltage lock on. I would change the bios but it isn't really worth voiding the warranty