Mac Pro 2009 - Where are the northbridge-chips?

[FFder1.]

Hey,
i am an owner of a 2009 Mac Pro (2x2.26, 4.1).
Because i am a friend of cool systems, I changed my graphic card fan and added an active cooling system for my RAM. The only hot parts of my Mac are still this mysterious northbridge chips (with ca. 70 °C).

So is my questions: Where are this Northbride chips?
A simple picture would be awesome.
I ´ve recently read many debates about the heat of the Northbridge, but nobody wrote, where there are. So I don´t want to start a new thread concerning the topic, how hot the northbridge chips should be.

 

[666sheep]

https://forums.macrumors.com/posts/11088953/

First pic, under this heatsink, located between right CPU socket and left RAM slots.

 

[nanofrog]

It's located on the daughter board under the heatsink next to the CPU socket/between the sockets on a DP version (same board the CPU/s reside on). See pics in link above.

BTW, It's not really a Northbridge any longer, as the memory controller is now located in the CPU itself. The chipset contains the PCIe lanes and communicates with other parts on the board via a DMI (i.e. ICH = SATA, USB, Ethernet, PCI,...; PCI bus is used to communicate with other components not contained in the ICH itself, such as the Firewire controller).