Or you could look at it another way, as a safeguard; especially so with the 7900 GT's. A lot of those cards went the way of the dodo when they were overclocked, or never clocked the same again even struggling to run at the speed at which they were originally released. This is the very reason I bought my factory oc'd 7900 GT, so at least if it went arse up it was still under warranty.