What is this iMac component

The computer is an iMac 8,1 2201 Early 2008, HDD has been replaced with a SSD awhile ago.

Recently the GPU die temperature has jumped up for no reason. I usually pay attention to the CPU temperature, not the GPU so not sure exactly how much it has jumped up, but it's about 10 - 20 degrees Celsius, now hovering at about 80 degrees Celsius.

This is normal day to day use, no games or heavy resource use software, and it just went up for no reason. I opened up and cleaned it because it was quite dusty and gained about 5 degrees, but it's still around 80.

What I noticed after I opened it is that all the parts had cooled down, including the GPU, except this component that is next to the SSD and on top of the GPU.

It could be this component that it's the culprit and not the GPU so I was wondering what it is. I have attached a picture in which you can see the SSD and this component.

Maybe you could help me identify it.

Thanks