You what i am glad you asked me that because i was about to start a new tread on my temps. the reason for it, on my 965 each core temps were at 94F thats overclocked at 4.0ghz at adverage load, but now sense i put in the 1090t my core temps at 4.2ghz runs no higher then 75F at adverage load. i did use a little more thermal grease maybe on this chip, than i used on my 965, but the ultimate question is WHY??????
Maybe your 965 setting, the waterblock was not properly seated, maybe there was an air bubble in the TIM between the water block and the CPU, ambient temps have a lot to do with it also. It can be any number of reasons.
Also, temp monitoring software have a tendency of mis-reading actual temps on the hexa cores. Try using the BIOS reading as a guide. I use Aida64 which gives me an accurate CPU temp reading but the core temps are low. See if your MOBO manufacturer has a temp monitoring software that you can install and try reading off of that.