Corsair Link software seems to be broken after Windows 8.1 update. Fortunately, there is a fix.
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Hit the start menu, and type "regedit" (Registry editor). Right-click it, then choose "run as administrator" to gain the needed privileges
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From the left side folder tree, navigate to the following key:
HKLM\SYSTEM\CurrentControlSet\Enum\USB\VID_1B1C&PID_0C04
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Navigate to "Device Parameters"
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Change the following DWORD values from 1 to 0
AllowIdleIrpInD3 DeviceSelectiveSuspended EnhancedPowerManagementEnabled SelectiveSuspendEnabled
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Do this for every sub folder inside
VID_1B1C&PID_0C04. In my case, it’s just one folder. - 
Restart your machine
 
After restarting, you will notice that the missing LED controls and fan controls are visible again.