Is that 2.8GB of memory? If it is, what processor do you have?
If you've got an E7400 (ie, 2.8GHz) and a G31 chipset, then that's 10.5 x 266. Anyway, you can go up to 333 with G31s. Some G31's will fall over a few MHz over this, maybe 340, others go further. If you've already go a 1333FSB processor then there isn't much room to move, but if it's 800 or 1066 then good.
In BIOS, go into MIT, enable the host clock and go to 300 or 333 and see how you go with standard voltages. Keep your memory frequency as low as possible to start with (ratio 1:1 or so). It should be ok.
Yes, there is plenty of reading out there on this. Everyone has a different idea.