I know I asked this same question on a different post pertaining to 990FXA-UD3 (rev 1.1) Northbridge, and did get the same answer.
I feel this to be relevant to all; so I moved to this thread seeing someone else has the same thing going on.
But, I still need more Vital information; the info that was given to me was indeed greatly vital. Thank you!
Here is what I did to try and combat the heat problem.
Removed heat-sink took off plastic and rubber sticky material that was cut out to allow the chip to fit into center.
Cleaned heat-sink and NB-chip top with Isopropyl Alcohol 90% thoroughly, polished HEAT-SINK where the chip touches heat-sink to attain a mirror shine.
Use good quality SILVER thermal paste drop on NB-chip surface (not so much it squeezes out).
Replaced heat-sinks original fasteners with nylon screws/ nuts (Fry's store size #8), snugged down a little better than the old original spring loaded plastic push pins.
The heat-sink doesn't move at all now much like it did before.
Mounted a 60mm fan to it, which was NO EASY task.
DID test both video cards separately (2 GTX 550 Ti) in my old Gigabyte EP45-UD3P so I can gauge a control.
What I now have is this: NB test
Ran 3 applications each and than ran them all at once got a .5°c + or - variant. Apps were ArmA 2OA, and .avi video at full screen, and a Youtube video.
My temp were taken from two (2) points on the heat-sink block, (tall, than flat/short spot) so there are (2) readings.
Temps for running all (3) Apps: 47°-53°C or 122°-127°F
Please remember from my other post "I NEVER OVER CLOCK".
Used a Laser/ Inferred gun for all temps. Used temp, gun to make sure the SLI video cards were operating.
Time to preform all the tests 12 hours.
Still have a questions/comments for the pros.
I should not have to do all this if I am running stock/default settings. True?
However the plastic spring loaded push pins that attach the heat-sink may have allowed the Northbridge heat-sink to unseat from the factory thermal tape. True?
I have been very careful to avoid scratching the motherboard and have not scratched it at all nor have I altered the motherboard.
Will any of the repairs or modifications I have made void the 3 year warranty?
P.S. The electrical smell is seeming to slowly dissipate; and this Motherboard was purchased in November 2012 and put into service.