I am running Macbook Pro 2012 with upgraded RAM and SSD. I bought it with Mountain Lion then , Mavericks and then upgraded into Yosmite . running latest 10.10.5 , for at least one year I am facing every now and then sites opening error , sometimes it does not come for 1 month , sometimes it bugs me everyday and now for one week , I am pretty tired with it. if I open a site in Firefox or in Chrome , it does not open and got "not found" error in no time, surprisingly if I use Tor browser , it opens next second, further more torrent clients work like a charm , I clean history , reboot modem and using
sudo killall -HUP mDNSResponder
in terminal often , its like shooting in dark , sometimes it works , sometimes it does not . I can say I have no idea why most of sites just gone to "not found" and how it can be fixed, I have gone through several articles but none of them seems to work perfectly ok for me.
should I wash away my SSD completely and install a brand new Mavericks copy to solve this ? would it I have to reserver some kind of serial numbers to install a fresh copy ? or I just download Mavericks and run it on a brand new HDD ? I also want to add that since last some updates I have found that my RAM got exhausted a lot , I was using 8 GB (2x 4GB) but last month one RAM is fried and on replacement , I have found a single 4GB RAM exhausted most of the time , free memory status never went up more than 800MB while not a single app is opened except Finder.