pelister,
Welcome to Tom's!
Core 0, 1, 2 & 3 in SpeedFan correspond to Core 0, 1, 2, & 3 in Core Temp.
Whenever you see temperatures in SpeedFan or Hardware Monitor that have values of 127 or 128, these indicate unassigned inputs which are erroneous, and can be ignored.
In your screenshot, SpeedFan provides for an analog "CPU" temperature sensor which is present on older processors such as Core 2 and 1st generation Core i variants. Since your 4th generation Core i processor doesn't have an analog "CPU" sensor, you can again ignore that input, which is also erroneous.
You can turn off unassigned sensor inputs in the "Configure" button. From there, you can also set the "Warning" temperature for each device, which will determine...