Conky , issues with HDD name change

[antcj]

Ist up ,noob here.
Mint 13/ mate/ 32 bit
I have had conky running for a few months. (Rather a messy file now, i should clean it up .)
Anyway, now and again i notice the screen (conky) widens on boot. When this happens it refers to one of the HDD (2nd data) when it tries to get temp info.
Conky is set to look at sdb. looking in gparted the name changed to sdf.

as below is how it was

HDD OS Temp ${execi 10 hddtemp -n /dev/sda}°C
HDD Data Temp ${execi 10 hddtemp -n /dev/sdb}°C

so i changed the b to f

HDD OS Temp ${execi 10 hddtemp -n /dev/sda}°C
HDD Data Temp ${execi 10 hddtemp -n /dev/sdf}°C

the problem is, it may well change back as its done before.

Has anyone else experienced this?
appreciate all help