1500 / 4 = 375. 375 * 8 = 3000GHz. Can't figure the ram speed but sounds like you are using ~ double the FSB. Assuming you are using 1600MHz ram that shouldn't be the issue. Nice to see the voltage isn't to high.
What happens when you use 400FSB? Drop the CPU multiplier down to 6x. This should give you a 2.4GHz CPU. But it will tell us if your Nvidia chipset board can even handle 400MHz.
my CPU multiplier is already at 6.0, my Ram is 1600MHz but this motherboard only accept 1333MHz ram (or 1600MHz overclocked), and i only got it around 1400MHz (i selected an memory level up to pc3-11... dont remember very well) tommorow i will bring some screenshots because i'm not at home and don't got my pc here