Help! Overclocking failure

Hello. My system specs are: Windows 7 Ultimate 64-bit, Intel Core i5 3470 @ 3.20GHz ,RAM8,00GB Dual-Channel DDR3 @ 665MHz (9-9-9-24),MotherboardGigabyte Technology Co., Graphics(1920x1080@60Hz)1535MB NVIDIA GeForce GTX 560 SE,Storage232GB Samsung SSD 850 EVO 250GB ATA Device (SSD). The problem i had started after i tried to overclock my ram from 1333mhz up to 1600 using another profile from bios settings. I saved and exit the changes the pc boot up and i opened a game to play(League of legends). I get about 250-300fps on medium settings and out of a sudden i noticed i had barely 90 fps. I was really confused and didnt know what actually caused so big fps drop so i joined another game to figure out if its only that game. So i opened World of warcraft in which i have 100 fps and then i saw that my fps was down to 25 !!!! From Speccy i saw that my Gpu had 70Celcius steady while i had a game opened and down to 65 on idle. That was really strange cause before a month i changed thermal paste on my gpu and the idle temp was 30 and went up to 50-55 max while i was gaming. I was really scared and didnt know what caused that problem so i remembered i did that overclock the other day. So i quickly restart my pc and go into bios and reset to auto profile my ram speed (1333mhz) as it was. Computer starts i open quickly League of legends and my fps were the same as it was! Finally 300 fps again and 0 lag in game as i had before the overclock. After i finish my game i open World of warcraft too and i am shocked seeing my fps being 25(max) again!!!!!! I didnt know what to do or how to fix this cause i have 0 experience on overclock etc so the same day couple of hours after i came to the conclusion to format my pc and hope that the problem goes away. At last after i formated my pc everything is back normal! All games i played (leagueoflegends,worldofwarcraft) have the same fps again and no lag at all! Anyone knows what might cause that? Cause its really strange after the OC i did to my ram my fps dropped sooo much and my gpu overheated with nothing open!. Please share your thoughts if you know anything or you have experience on my problem. Thanks a lot for reading.