You'd have to remove it before reapplying - also, be careful not to apply too much.
As for the bios settings the gigabyte x48's are very stable (my x38 is similar) so all i would start trying is upping the cpu voltage to between 1.3v and 1.33v (try the lowest first and work up).
Also, your DDR2 will need to go slightly beyond its rated speed (why i have PC8000) - you only have 800mhz DDR2 so it will need to run @ 421mhz to get the e8500 to 4ghz.
gt
As for the bios settings the gigabyte x48's are very stable (my x38 is similar) so all i would start trying is upping the cpu voltage to between 1.3v and 1.33v (try the lowest first and work up).
Also, your DDR2 will need to go slightly beyond its rated speed (why i have PC8000) - you only have 800mhz DDR2 so it will need to run @ 421mhz to get the e8500 to 4ghz.
gt