I find it unlikely that the age of the sensor is resulting in a 1 stop difference in noise level now vs earlier. One possibility is that you're using a newer version of Lr than when you first started using the 1Ds III. The earlier versions of Lr used so-called "process version" 2003 which had a lower-detail interpolation and sharpening. With Lr 3 in 2010 (and continuing through Lr 5 at present) the interpolation and sharpening have been improved for higher level of detail, but also with preserve more noise inherent in the capture. So, if you are thinking about pictures you may have imported into Lr a few years ago, vs now, that could be one reason you're seeing a difference. If you want to remove the noise, you can use the noise reduction tools in the Detail panel. (Previously in Lr 1 and Lr 2 there was some noise reduction happening under-the-hood that could not be turned off by the user.)