Need help Overclocking on my Asus M3A78-EM

Hi,

I am new to overclocking. I went through some guides and decided to test the maximum possible reference clock possible on my board. I underclocked my cpu, ram and ht multiplier to do so. All my voltage settings are at defaults. PCIE set to 100.

So far I have got the following results-
CPU frequency2330
HT Link1096.8
Memory332.73
CPU Multiplier8.5
HT Multiplier4X
HT Ref. Clock274

As soon as I try to take it to 275 my pc hangs. Can I take it higher.. am I doing something wrong. Is this okay for this board or can it do better.

I also have the following questions and it would be very helpfull if anyone could answer them.

1) This board does not have any heatsinks on mosfets. Does this mean I should not increase the Cpu Vcore and Cpu Nb volts? What exactly heats up the mosfets, increasing the voltage, increasing cpu clock speeds or increasing reference clock multiplier.
2) The is a setting called Chipset voltage in my bios, what is it for?
3) I can increase the cpu and nb volts only by the following values - .05, .1, .15 ... Is this sufficient for moderate overclocking.
4) Can increasing cpu and nb voltage by the maximum (.15) damage my board.
5) I tried to overclock my 4400+ Brisbane on stock cooler with processor overclocked to 2750 Mhz at a reference clock of 250 with HT multiplier at 4. Cpu vcore and cpu bn volts were set to +.05 . I got 1 error on prime95 after 5 minutes. Will getting a new aftermarket cooler solve this problem. Or is this problem due to low voltage. The temps reached at about 62C.

It would be great and very helpful to me if any owners of this board could post their overclocking results here.

Thank You