Question H60 overheating somehow


So I'm using a basically new in box first gen H60 watercooler to cool a i7 3820 and it's constantly giving temp errors. Just sitting in the bios I see it heating up from 37c to 80c and then shutdown.

Now I checked if the h60 is working just fine. Pump is running at 4000-4300 rpm, I can feel it running and one of the tubes is really hot and the other is nice and cold returning cold water. So it's doing it's job just fine.

As far as I know a h60 should be able to handle a 3820 at stock shouldn't it?

Edit: This h60 has been with me for years and was originally for a fx 8350 build but I ran into clearance issues with my case so it's just been sitting on the shelf being used to test a system here and there. I would be surprised if it has been used for over 200 hours even.
Got one of those temperature sensor guns from my neighbor and well it seems the h60 is acting up. Coolant temp is about 17c colder the moment it reaches over 50c and pretty much retains that till I reach 90c and go into thermal shutdown.