No worries about that 128° temp reading. My Agility 3 also reads that temp via harware monitoring utilities & in SMART.
I've just placed a fancontroller and placed one tempsensor on the bottomside of the SSD (with one fan from front and one from below on it) and that reads 27°. I've a 2nd temp sensor on bottomside of my WD hard disk wich sits right above the SSD and that one gives 31.8°.
I'm going to get another hard disk to put a reserve OS on for in case ever happen something to the SSD, then I can also check that the SSD causes the main OS drive to read 128°. When I first connected the Agility to update firmware before install OS on it, it was my WD hard disk that readed 128° and the SSD readed a normal temp of 30°.
Still it is a little bit annoying it doesn't give correct temp via any hardware monitoring utility.