Thanks for the suggestion, i'll have a play with the settings tonight when I'm home from work.
Andrew
I installed Afterburner and here are the results.
Memory Clock set to 1100.
I firstly used a graduating fan speed and this got the GPU up to 97C and then World of Tanks froze, I did CTRL+ALT+DEL and got into Task Manager and closed down WoT.
I then set the fan speed to 56% and tried WoT again and the GPU got to 59C and WoT froze again.
In both instances when I closed WoT there were sparkles on my desktop, only after the GPU cooled down enough did the sparkles disappear.
I look forward to your next suggestion after you have taken a look at the log from AfetrBurner.
Many thanks
Andrew