In case you forgot, a tutorial.
http://www.sevenforums.com/tutorials/66504-processors-limit-number-used-windows-7-a.html
hello sir,
i have acer aspire v3-571g laptop with windows 8.1 x64 based OS. Processor is Intel Core i5.
To get a faster booting, i selected 2 processor instead of 1 in advanced boot option (msconfig) by mistake and now my laptop become dead slow on booting and startup.
I am in a big headache now...
Please help a hand to solve this issue...
Thank you..

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic