BSOD 0x0000003b light load.

hi guys, i seek your wisdom. (theres a story so please bare with me)

I recently built myself a new gaming pc (specs to come).
All was well and good, until i got my first BSOD and by first i mean my first ever in my many years of pc gaming/building!
They repeated all night when doing simple tasks like installing games and even at idle.
I had recently upped my ram voltage to 1.65v as thats what asus stats my ram needs to run at to be at stock 1866mhz.
But stupidly before i thought that being the issue I formatted windows, and then changed its voltage back. problem solved... played crysis maxed out all night and no issues. however today when downloading Ie9 and updating steam games i get another..

System:
Windows 7 Ultimate x64
Intel core i5
Asus P8Z68
Corsair vengence 8gb DDR3 1866mhz
Ati HD 6950
Cooler master extreme 650w PSU
Antec 900 case

Thanks for your help and i hope i didnt break any rules getting this zip stuff :)

Thank you for a speedy reply.
Before i formatted i tried to get the latest drivers but ATI and also its auto detect program said i had the latest. But i will follow your wisdom.

On a side note, windows starts then says update fail shutting down. it does this 4 times and then loads properly, restore does nothing and update keeps failing once in windows. this isnt a main concern as im upgrading to a SSD soon so will have a fresh install. just the BSOD thats bugging me.

thanks again Adam