down clock to 1v?

ya, have to do it with caution, but your board have dualbios:
http://www.gigabyte.my/microsite/55/tech_081226_dualbios.htm
i think other method is more safe than flash bios in windows environment.

2.8ghz on 1.15v?

2.8ghz on 1.092v, not bad at all.
continue try out see what is the lowest stable vcore for 2.8ghz.

really awesome man 

like my processor amd 960T -- usually i set my vcore voltage about 1.325V ..

question [ set higher voltage as what i did now can reduce the cpu life span ?? ] 

2.8ghz on 1.092v already very nice.
how is the full load temperature?

god level full load temperature.

reset bios?
reassemble the rig?
try other cpu on it?
update bios?
try unlock core see any change in bios?

haha, no wonder.

it either the chip itself, not the brand. wanna try other mobo? i have 3 with me right now :
Sabertooth R2.0, 990FXA GD80, Crosshair V Formula. just come to my place,
bring your processor, mobo and hdd <-- hdd and mobo : incase i need to see your bios and try out 

of course all these boards were not in the same league with your board. i don't have any high-end gaygay board

*take note that my 960T also cannot be unlocked now, but can be unlocked to 6 core when newly bought

this is really f*** ..  i need to reset my bios again when i try to unlock to 6 core.. 

omg!! I have a bad impression toward gigabyte mobo now ..

nice, looking forward to your overclocking result.

i really really appreciate with your offer lengchai ..

as i told you i dun have transport but its okey la -- i will try to figure out until i suceed or else i will take back to my vendor to help me check 

*take note my gaygay mobo is really naughty 

proud of you la bro    good idea ...

nvm la. . i need to use my desktop to do my assignment and other work too ..

i also cannot take back for warranty unless i having semester break =p ..

Some recent OC after replacing the stock HSF. 4300MHz @ stock Vcore
Looks like my chip is more suitable for downvolting.

Nope. This is already the minimum Vcore it needs for 4.3GHz with OCCT 1 hour stability test. 
It can perform at low Vcore for stock 3.5GHz @ 1.15 V and the Vcore scales linearly till 4.3GHz. I haven't really try any stability test past 4.3GHz. My power supply may not able to provide enough juice 

ah boy bro david is no new comer lah... i learn alot from him back then & i'm still learnin from him now. 

Nah me already retired long ago.    Missing out a lot of things since then...hahaha. Need to learn from you 
BTW, what r u using now? Any recent OC?
Nah it's still fine. Just sometimes it's frustrating because Vcore is a tad inaccurate due to the way offset works.
No budget ler.... 

no point goin for fx at this point of time, pii x4 still a decent chip for gaming purpose. wait for d launch of streamroller then only decide. 

HoNeYdEwBoY The temps so far so good. Slightly better than last time. But i think 4.4ghz is max for my Fx 8150.