Just as an update.
As for the restarting on boot up, its seems like a common problem with this motherboard, referred to as boot loop/cycle. If you read customer feedback on http://www.newegg.com/Pr...px?Item=N82E16813128498
or even just search Google your see that Gigabyte boards based on Z68 chipset have this issue.
To make sure there was an actual problem with PC i took it into my local computer repair store (Computer connections, Hastings). After handing them $100 they informed me that the PC was having issues. More specify they found that the PC would shutdown correctly if they removed the graphics card. To exclude possibility of defect video card, they tried multiple other cards and were able to reproduce shutdown issue. After excluding other components (by testing in another machine/replacing them) they concluded that their is mostly an issues with motherboard.
I'm initiated the RMA process and hopefully will get my MB repaired/replaced for a working one. I've also purchased a new MB, ASUS P8Z68-V PRO/Gen3 as my replace in the meantime which i will most likely keep. Whats the chances on the Asus being DoA....