By against, a material analysis made with PerformanceTest shows that these cards are in reality DR2 667 MHz PC2-5300 PC2-5400 sold by elsewhere by the same supplier. I suspect this provider to have only one real reference for sale and meet demand by this subterfuge.
In addition, although Windows confirm that I am gone from 2GB to 4GB of memory, the actual physical memory only increased from 2GB to 3.5Go.
However, performance seems to be better.
Finally, satisfied with the quality / price but no more: if you want to be sure of what you get and achieve the expected performance, order them from a reliable supplier.