Well I managed to OC up to 2.8 at stock voltages and cooling, temperature during stress were around 60C sometimes less. Left RAM clock speed to 840Mhz and seems working fine.
And last but not the lest GPU. I don't understand somethings about it. I use nTune and after OCing it when I restart the speeds all go to default (when restarting pc turnsoff for a while and launches agen). Is there some problem in Bios?