There was such an article in the magazine, issue 65, February 2009 - so it is now missing several new models. Online it can be found at http://www.custompc.co.uk/labs/247615/nvidia-geforce-gtx-280.html and linked pages. The easy-to-understand graphs and summary seem to have got lost in the move
There's an E-Cookie for the first person who can find that .xls file with all (read: most of) the nVidia cards and their PPD values. Haven't looked for it myself but I'm sure someone can find it! EDIT: Not what i was looking for but very handy for seeing what kinda TDP and exact processing power/ stock speeds your nVidia hardware has, I've used this bookmark more times than I can remember. nVidia GPU Comparison