I think it is because for whatever reason my 2nd WIN SMP client is never stable, very rarely did it go through a whole WU even when my machine was a stock with everything running a snail pace.. I may look at running 1 WIN SMP and 2 console clients to see what output I can get..
) and the RAM is 1000MHz stuff. I set about overclocking it. I set the CPU to 2.7GHz - everything fine. I fiddled with the RAM and managed to get it working at 900MHz at 4-4-4-12 - excellent, I thought. I set it going and the frames were no longer taking 17.5 mins ................ they were taking 20.5mins 
It EUE'd my F@H but it worked fine otherwise.