IIUC, you are saying that Attribute 190 and Attribute 194 in fact refer to the same temperature sensor, despite their different names.
So the max/min/current values for the current power cycle would be 53/19/50C, and the max/min lifetime values would be 60C and 11C, with the reported value of 40C being in error?
Elsewhere you have stated that the read heads are themselves used for temperature sensing, by virtue of their thermoresistive properties. This brings me to the following thread where it appears that a particular Seagate drive has a faulty temperature sensor:
http://forums.seagate.com/t5/Internal-ATA-and-Serial-ATA/2-Barracuda-7200-11-failing-miserably-HELP/m-p/47552#M18828190 Airflow Temperature 45 47 37 069135300035
194 Disk Temperature 0 53 63 000F00000035
1 Raw Read Error Rate 6 119 99 00000C2DE92D
5 Reallocated Sectors Co.. 36 100 100 000000000000
197 Current Pending Sector.. 0 100 100 000000000000
198 Off-Line Uncorrectable.. 0 100 100 000000000000
My first thought is that attribute 194 is not reporting any value for the maximum lifetime temperature. I'm therefore wondering whether you have misinterpreted the structure of the data???
Secondly, if the read heads are responsible for the faulty temperature measurements, then shouldn't we expect this to be reflected in the read performance?