The Blackmagic Intensity Pro 4K HDMI capture card comes with a stock cooling solution that is not adequate for the job.
After browsing for a while I stumbled upon a 40x40mm (60mm diagonally) heatsink that serves as a perfect replacement for the stock heatsink:
Before putting the new heatsink on the the FPGA chip, clean the surface thoroughly with isopropyl alcohol and make sure any remaining residue from the stock thermal pad is removed. Then apply some Artic Silver 5 cooling paste on the FPGA:
I then decided to pair this heatsink with a silent 40mm Noctua fan.
The Blackmagic Intensity Pro 4K requires a 5V fan with 3 pin connector so i chose the Noctua NF-A4x10 5V:
After stripping some wires and some soldering, the final result looks like this:
The only downside of this mod is that the capture card now uses 2 slots inside the PC instead of one, but at least it does not overheat anymore now 🙂