Notebook cooling pad - compensate for CPU temperature sensor dysfunction

Two weeks ago I had the nVidia GeForce 8400M GS GPU (and motherboard) replaced in my XPS M1330 notebook PC under Dell's extended nVidia GPU warranty.  During the testing process to ensure no other problems, the Dell technician discovered that the Intel T9300 CPU had a non-functioning temperature sensor.  As most of you know, this means the CPU will not activate the fan properly if it overheats.  The CPU is an engineering sample (ES) (I had bought the PC used and the original owner had upgraded the CPU with this) and I understand now that most Intel ES CPUs do not have a functioning temperature sensor.  (Of course I wish I knew this before I had bought the PC!)  Prior to the nVidia GPU replacement I had noticed the PC sometimes became unusually hot after prolonged use and I would turn it off to allow it to cool.  The Dell technician surmised that excessive heating due to lack of  temperature sensor function may have damaged the nVidia GPU and possibly other components of the motherboard.  Since I received the PC back from Dell, it has been operating normally and I am more careful to watch (or rather feel) for overheating and to turn off the PC more often.

I also purchased a Titan TTC-G4TZ (sometimes abbreviated G4) cooling pad two days ago.  It has four fans and an aluminum surface and is powered through the UBS outlet on the PC.  The pad seems to keep the PC notably cooler than without the pad, even after running it for 10-12 hours.  Every 15-30 minutes I feel the keyboard and the entire area below it and the entire back area of the PC and no point feels more than mildly warm.  If I used the cooling pad constantly when I use this PC with its ES CPU, will this be sufficient to prevent internal overheating and compensate adequately for the ES CPU's lack of temperature sensor function?  I know this is highly subjective, but as long as the PC case (entire back and front, including keyboard) is only mildly warm, can I assume the PC's internal temperature is not excessively high?

If I decided I needed to replace the CPU, are there any long-term pitfalls to buying a used one?  This assumes, of course, that the CPU works normally upon installation and most used CPUs seem to have a DOA guarantee, at least for exchange.

Thanks for any suggestions and opinions.