Cards being unlockable is certainly not fiction - I did it myself years ago with the ATI 9800 SE AIW. It turned 4 pipelines into 8.
However, it seems from the comments here that you are very unlikely to get an unlockable 465 now. Personally, I'd just go for a GTX 560 and be done wih it: better performance, much better thermals and really quiet. Have you seen W1zzard's reviews on TPU? If not, click the links below. The first one links to the reference 560: