You're measuring theheatsinkand not the casing of the IC.
The casing is likely hotter than that.
The current generation of organic packaged Northbridges are
good for about 99C case temperature. You can find the
chipset on the Intel site, find the thermal design document,
and get a Tcase max from there.
In a previous generation, where ceramic packages with glass frit
seals were used, chips could take about 135C. The temperature
has dropped, with the move to cheaper organic based packaging.
It is likely the packaging is degrading at that temperature,
rather than the silicon being in danger.
For info on whether your SuperI/O has a hardware monitoring
interface, you could check the list here, and look for
the SMSC chip on one corner of the board. (Alternately,
you could download Speedfanfor Windows, from almico.com
and see if it detects thermal sensors.)
http://www.smsc.com/main/catalog/desktop.html
This is a picture of a motherboard for the 4600 from Ebay, and
the SuperI/O appears to be the chip in the lower right corner.
This is how I guessed the chip involved is from SMSC.
http://www.redplanettrading.com/ebay/motherboards/2y832/top800.jpg
You could perhaps fit a 40mmfanto the top of the Northbridge
if you wanted. Sometimes theheatsinks are designed, such that
the four screws that fit in thefanholes, are an interference
fit between the fins. But be careful, because as you tighten
up the metal screws, they bite tiny bits of aluminum filings
from the blackheatsink. Aluminum shavings could short out
closely spaced conductors on the motherboard.
Replacing theheatsinkwould be another alternative, but the
options available to work with the clip on thatheatsinkare
limited. I was thinking something along the lines of a
Swiftech cooler, but the Swiftech uses screws. Fitting a
different passive cooler isn't likely to help much.
http://www.swiftnets.com/products/mcx159-CU.asp
I don't think the chip is in danger, but if it concerns
you, then fitting afanmight be arranged. On some
motherboards, the design intent is that side spill
air from the output of the CPU cooler, cools the
Northbridge. But with a Dell product, they're likely
to use a shroud for CPU cooling, which means the CPUfan
won't be cooling other stuff on the motherboard.
The noise from thefanmay bother you. A 40mm could run
at 6000RPM. You could try a largerfanand an
adapter, but then you have to figure outhow to
safely hold it to theheatsink, without mechanically
damaging something. This product is just to illustrate
how you'd fit a 60mmfanto a 40mm application.
http://www.performance-pcs.com/catalog/index.php?main_page=product_in....
Paul