ASUS P4G8X Deluxe offers robust overclocking options to maximize your system performance.

Flexible CPU Core Voltage Adjustments in 0.025V increments over defaults
SFS (Stepless Frequency Selection) from 100MHz up to 400MHz at 1MHz increments
Fixed AGP/PCI frequencies
ASUS propritary C.P.R.(CPU Parameter Recall)


That is from ASUS, so it would appear that your fsb should reach 400...
http://www.hexus.net/review.php?review=493&page=11

Have a look at the site above, it states that upping the FSB is a bit of an overkill.. :P

I agree with Phish here on this one.

My question now is, what kind of ram is it?