Depends on the model! I made a previous purchase of a Crucial Ballistix 2GB (2x1gb sticks) 1066 kit and it was terrible - and only after I got them did I investigate the matter and found complaints after complaints. I since then ditched Crucial (I never had them before or since) and went back to OCZ, but now I switched to g.skill. Both are great, and never had/have any problems with them. In fact, my OCZ kit (which was over a year old when I made the decision to try Crucial) overclocked better and never became unstable even though they were rated much lower than the Crucial which were rated 1066 but were never even stable at that speed, instead I had to run them at 800 and even then they were crappy. Anyway, do your research before you buy...and don't depend on brand name alone! Good luck.