But with the lower multiplier means lower temps.
Which allows you to up the FSB without the temp gain.
^Full of crap
Any given chip has a top speed that it will run at. The key is to hit that speed while also hitting the top speed your ram will run (or your mobo will allow the fsb to run), this is why the multiplier tweak is so nice.
Temps are not going to increase noticeably by simply running the chip faster, they are going to increase when you start to increase the voltage (a good way to get a few extra mhz, or a few hunred extra for that matter)
SO the moral of the story, drop the multiplier as low as you can and start bumping that fsb up until it can go no higher. Once you determine that top speed, stick with it and start increasing your mulitplier. Easiest way to do it.
However if you are fooling with an Intel chip the only way to mess with the "multiplier" I know of is to tweak the ram:fsb ratio. Although you arent literally changing the cpu multiplier, this is effectively what is being done.