It might help you shave off a couple degrees for maximum performance but if you already have a tube of AS3 then I would just use that one and not bother with it. I mean your cpu will not last longer if it runs at 50*C vs. 55*C. It matters in cases where you run almost on your limit so to stop the CPU from scaling back and dropping clock speed, but I am sure you are not running your Athlon at 75*C or your p4 at 70 or whatever the limits are so you shouln'dt worry.
But for best performance AS5 is hard to beat.