need help with overclock settings

[xxcoop42xx]

here's what nvidia control panel is set to:

under the CPU tab: fsb clock speed=374mhz, cpu core voltage 1.35

under motherboard tab: fsb clock speed=374mhz, nforce mcp core=1.250, fsb=1.3.
this achieved a 2.8GHz CPU speed.

a few questions about this,

are these ok overclock settings?

while i was typing this i started to smell what seemed like smoke so i returned the above settings to normal and the smell is gone, why did this happen? i guess the voltages are too high?

what is nforce mcp core?

is that another way of saying CPU core voltage?

should the mcp match the cpu core voltage?

any and all help would be great, the mobo im using is a dell/nvidia nforce 650i SLI board.

 

[xxcoop42xx]

i may have a theory about this. the mobo in the xps 630i is a dell/nvidia 650i sli mobo with the highest supported cpu fsb of 1333mhz. now this is where it gets confusing. i cant change the fsb(QDR) in the bios at all. its at 1333 and if i change it to 1334 the pc doesnt post. but if i load vista and go into the nvidia control panel i can overclock the cpu to 2.7GHz from 2.5GHz(stock) without changing any voltages. so with the cpu fsb at 360mhz that means the QDR is 1440mhz. and i make this oc profile and save and create a auto load rule so after i login to windows after 3 sec it will load the oc settings. now why can i oc with the software but not in the bios? its very frustrating and i would like to be able to oc in the bios instead of software. but since the mobo has max fsb of 1333mhz for cpu, is that why i cant raise it because its maxed already? but why does it work with the software. and the oc is true after software oc it shows in cpu-z and 3dmark vantage. so if any one can explain why i can software oc but not bios oc its greatly appreciated.