Corsair has always been a respected RAM-manufacturer, keeping a good pace with the competition. They have now gone past OCZ and GeIL in terms of clockfrequency with their new TwinX 1024-4400 and CMX512-4400 modules. As the name implies we are talking about 512MB modules reaching the standard PC4400. PC4400 corresponds to a clockfrequency of 550MHz DDR, opening for the opportunity of a 1:1-ratio up to 275MHz.
Every module was tested on a Asus PC4C800-E in 550MHz with timings set to 3-4-4-8, with voltage specified to 2.75V.
You can read more about them, here.