GA-P43-ES3G Problem with Nvidia GTS 250 512 MB

[DeJaVu]

Hi all,
Im having an issue with the fore-mentioned motherboard.
My configuration is as follows:
MB - GA-P43-ES3G
VGA - ECS Nvidia GTS 250 512MB
CPU - Intel Q8200@2.33
HDD - 2x320GB WD SATA2
RAM - 2x2GB Hynix DDR2 800
PSU - Enermax Liberty 500W two 12 volt lines 22A each ,combined 12 volt is 32A
Display - Samsung T240 DVI

When im playing a game , after some time (usually after 15 minutes or so) the screen goes blank and i can still hear sound for couple of seconds, after which the sound starts to stutter and the only way out is resetting the pc .
When i run OCCT Gpu test on 1280x1024 the voltage for the 12v line drops from 12.17 to 11.60 as reported by EasyTune . But when using a multimeter on one of the molex connectors on the PSU the voltage drop is from 12.20 to around 12.10 ,so by my logic that excludes the PSU being faulty.
Could there be something wrong with the Voltage regulation on the motherboard (is EasyTune to be believed?), or maybe it isnt even designed to provide that much power ,taking into consideration that it has a Q8200 which is TDP 95W and GTS 250 TDP 150W.
Any help or suggestion is welcome.    

[Beekeeper]

Hi
bios and drivers update would be good.
try to change the PSU and / or VGA and check how it will work