About 2 months ago I installed two SSD's in two computers. A Samsung Evo 500gb in an iMac 21 inch and a Samsung Evo 1 TB in an iMac 27 inch. For both computers we installed the Macs Fan Control app in which the SSD's were recognised as a Samsung SSD. We could set that the internal sensor of the SSD was used to control the fan speed. This worked really well until recently.
The Mac Fan Control for the 1 TB SSD still works fine. However, the Macs Fan Control app does not identify the 500 gb SSD anymore. The app does see that the SSD is there, but does not see it is a Samsung SSD with a heat sensor built in. As a result the fan is blowing at 5.500 rpm. I did see on your website a page which says that for SSD's the RPM should be set manually. But I do no understand why a couple of weeks ago all worked fine and now it does not work fine anymore. And on the other computer it still works fine. I would rather use the internal heat sensor because I know with heavy converting the fans RPM goes up.
I have uninstalled, restarted the computer and reinstalled the app. That did not help. I have now set the fan to 1.500 rpm manually because the noise was driving me crazy

Macs Fan Control 1.2.1
iMac10,1
Intel(R) Core(TM)2 Duo CPU E7600 @ 3.06GHz[100]
Mac OS X Unknown
Fans:
ODD-min{1000}curr{999}max{4350}mode{0}
HDD-min{1100}curr{1512}max{6300}mode{1,1513}
CPU-min{1200}curr{1198}max{4000}mode{0}
TempSensors:
TA0P (Ambient) - 30.1133, 30.1133
TA0p () - 33.75, 33.75
TC0C (CPU Core 0) - -1, 129
TC0D (CPU Diode) - -1, 129
TC0H (CPU Heatsink) - 52.25, 52.25
TG0D (GPU Diode) - -1, 129
TG0H (GPU Heatsink) - -1, 129
TG0p () - -1, 129
TH0O () - 9, 9
TH1O () - 9, 9
TL0P (LCD proximity) - 30.8438, 30.8438
TL0V () - 39.8711, 39.8711
TL0p () - 43, 43
TL1V () - 39.2188, 39.2188
TL2V () - 41.2383, 41.2383
TLAV () - 41.2383, 41.2383
TLBV () - 36.043, 36.043
TLCV () - 39.8711, 39.8711
TN0D (Northbridge Chip) - -1, 129
TN0H (Northbridge) - 65.375, 65.375
TN0P (Northbridge Point 1) - -1, 129
TO0P (Optical Drive) - 40.5, 40.5
TO0p () - 41.5, 41.5
TS0V () - 42.0625, 42.0625
TS2V () - 47.0508, 47.0508
Tm0P (Mem Controller) - 48.375, 48.375
Tm0p () - 48.375, 48.375
Tp1P () - 51.5, 51.5
Tp2H () - 57.25, 57.25
Tp3H (PSU Primary) - 55.25, 55.25
Tp3v () - -1, 0
Disk drives:
- 0
NVidia MCP79 AHCI:
Vendor: NVidia
Product: MCP79 AHCI
Link Speed: 3 Gigabit
Negotiated Link Speed: 3 Gigabit
Physical Interconnect: SATA
Description: AHCI Version 1.20 Supported
Samsung SSD 850 EVO 500GB:
Capacity: 500,11 GB (500.107.862.016 bytes)
Model: Samsung SSD 850 EVO 500GB
Revision: EMT01B6Q
Serial Number: S21JNWAFC08124E
Native Command Queuing: Yes
Queue Depth: 32
Removable Media: No
Detachable Drive: No
BSD Name: disk0
Medium Type: Solid State
TRIM Support: No
Partition Map Type: GPT (GUID Partition Table)
S.M.A.R.T. status: Not Supported
Volumes:
EFI:
Capacity: 209,7 MB (209.715.200 bytes)
BSD Name: disk0s1
Content: EFI
Volume UUID: 0E239BC6-F960-3107-89CF-1C97F78BB46B
disk0s2:
Capacity: 499,11 GB (499.113.771.008 bytes)
BSD Name: disk0s2
Content: Apple_CoreStorage
Recovery HD:
Capacity: 650,1 MB (650.117.120 bytes)
BSD Name: disk0s3
Content: Apple_Boot
Volume UUID: 5D58181E-60E1-3434-9BFB-80D561FEAD7B