My Computer Overheats all the time

hello my computer has been overheating quite often the past year my CPU ranges from 60C to 90C according to Hardware Monitor i tried installing another fan making sure it worked with the air flow ( one side brings in air the other side takes the hot air out) iv made sure its not dusty inside and the only thing i cant do is move my computer to a better place witch is probably the cause of the overheating ? its quite confined into a small corner i give it as much room as possible but other then that i cant think of any way i can make my computer to stop over heating i constantly have my computer turning off and i don't know if its my GPU or my CPU causing it i use 3d design programs and stuff like that often so its quite processor and Ram heavy most of the time and play allot of games on it. the GPU is kept up to date and iv made sure all the fans are running, though there is one thing to note and this could just be a cowincerdence but i added new RAM to replace my faulty RAM that i had for a year and ever since iv only then noticed my computer turning off due to overheating it could be that just never noticed it before due to the constant blue screens i got before i replaced my RAM but i thought id mention it just encase. Is there anything im missing ? should i invest in water cooling?

Intel Core i7 870 @ 2.93GH
8.00 GB Single-Channel DDR3 @ 667MHz
ASUSTeK Computer INC. P7P55 LX (LGA1156)
1280MB GeForce GTX 470