for 4.8 Ghz you will probably need to push close to 1.5V on the Vcore. I have no idea what voltage exactly, it varies a little based on the chip. I would start with 1.5 V and work my way down. Boot into Windows, run Prime95 for an hour (or however long you want, noone flame me pls) and then try a lower voltage if it's stable. If it's not, bump it up.
I wouldn't run 1.5V on that processor 24/7. I would keep it at or under 1.4V. Personally, I would settle for a lower frequency to achieve that.
Also, don't mess with the BCLK. Leave it at 100 for your processor. There is very little room if any for pushing that particular number. Get the multiplier to 48 instead.