This Nikon D800 vs. D700 ISO comparison was initially posted on the techbang.com.tw and my understanding is that it was later removed. I have not seen the original post and I don't know all the details, but I assume those are 100% crops. You will have to ignore the fact that all D700 samples are blurry and just pay attention to the ISO performance. Keep also in mind that the D800 was probably a pre-production version. I did not include the samples bellow ISO 3200 because there was no visible noise. You can click on the sample images for a slightly larger view:
The Nikon D800 and D700 cameras have identical ISO ranges with the only exception being that the D800 starts at ISO 100 (Lo-1 ISO 50) and the D700 starts at ISO 200 (Lo-1 ISO 100).