Hello there,
I recently bought my new pc with following specs:
Motherboard: P68 Intel X58
Processor: i7 930 2.8Ghz
Ram: Corsair XMS III 6GB
HDD: Western Digital 1.35 TB
CPU Cooler: Corsair H50
PC Casing: Cooler Master Storm Sniper

i then downloaded iATKOS_S3_v2 from demonoid.com but now when i boot the setup using bootable osx dvd. it starts and bring the first window. but then if i continue with the installation . it makes the computer restarted.
please anybody help me out.

Try this boot option

-x -v busratio=21 (and cpus=8 if needed)

See how it goes for you.