2.9v is considered by many people to be too high. If you have no problems, good airflow, and some active cooling then you're probably ok. PC3200 is getting fairly cost effective, you might consider getting some and not worrying about such a high voltage. BTW, most people, including Corsair warranty their products only to 2.8v. I think 2.8v is the specification maximum limit on DDR memory from JDEC. Can someone else back me up on that?
techfuzz