I have an asus M2n sli Deluxe motherboard, running an AMD athlon X2 6400 2.21 GHz, and I was thinking about switching it out for a newer faster cpu. This is one thing I have never really touched before, I have heard differing opinions about what is involved, would I need a different motherboard to run a newer cpu, even if it is the same socket type, would I need to reinstall windows, I have also heard that. Please let me know.
Windows keeps track of hardware changes and complains when too many are done, but a cpu upgrade alone will not trigger it. If still worried, copy your partition or drive to another drive as insurance.
The minimum BIOS version for the 6400 is 1102, so check to see what you have at start up or go into BIOS and look. Most of the Phenom X3's and X4's that suit require versions from 14xx to 16xx. Best thing would be to update the BIOS now to the latest version 1701 while the 6400 is in the socket. Once that's done you can toss in the processor you want to upgrade to.