A voltmod (solder/pencil) would be a problem if you know how to find it ....

A BIOS change may be a little difficult, but if the BIOS dosen't have the 862Mhz limit then drop it and do a soldering vmod

All you need is to find the correct IC and find the FB pin, then solder a VR between and off you go :P

Value on the VR you need is the resistens between FB pin and ground x20 roughly calculated

FB = FeedBack