no, you don't have to buy a new PSU, but if you're planning on running anything faster than dual 6600GTs, you should look at a new one. Just leave the top 4 pins of the connector open when you plug in the 20-pin PSU, and make sure you plug the molex connector into the EZ-Plug for PCIe stability. As for the Asus board, i hope it works better for you than me. My SATA-II controller died, so i sent it back and am currently waiting for a Chaintech NF4 Ultra right now (only $119 at newegg).