the option was not available in MSI AB 2.3.1 and for some reason MSI AB was not updating itself ,i have just installed 3.0.0 version and i fixed it .
disabling UPLS leads to slightly higher idle temps, and more power consumption .
u know , i should thank u for posting this thread because i was unaware of my gpu1 memory clock, it was running at 1500mhz all the time after i installed amd's 14.4 drivers , so i just reinstalled amd drivers and it is normal now as far as i am concerned .
check ur idle memory clocks (vrm) and ur idle core clocks , mine are running at 150mhz and 300mhz for both gpus (with UPLS disabled) .