I suggest leaving the computer off overnight so the temperatures will stabilize.
You may alos turn off computer, leave pump and fans to on at full speed and then try to cool down to the ambien tmeperature.
Then turn off the fans and pump and wait till it stabilize.
Second, check out also with external sensors, some may also have wrong offsets (so use two or three, and calculate average).
Good suggestion! It appears that the difference isn't as bad as I first thought - the MPS is still off but about +1.2C.
I'm using a standalone external temp. sensor and two AQ temp. probes to measure ambient.