Why don't people use multipliers 13.0 and above?

Why don't I see very many people use multipliers 13.0 and up? Do they want higher FSB instead?

Say you take a 133mhz FSB and use a multiplier of 15.

Does that pose the same stress on the CPU as using a 166 FSB and 12.0 multiplier (ignore memory/pci/agp FSB changes for now)?

I ask this because I have a soltek sl-75drv w/ 1800+ and I'm not sure if it has a 1/5 divisor.

So I think it would be safer for me to overclock using multipliers and a little increase in FSB. But, I'm not sure if I should unlock the L10 Bridge to get multipliers above 12.5.

Any answers to these questions would be great!
Thanks,
Vinh Sam

Upping the FSB increases the speed more, I don;t know why, but someone will explain it. The goal is to get low multis and high fsb.

Yes, but does stress on the CPU depend purely on MHZ? So if I use the multipliers to get 'X' MHZ will it put the same stress on the CPU if I use the FSB to get the same 'X' MHZ?

A cpu running at 1500mhz will be under a given load: it doesn't matter how you arrive at that speed, the cpu will be stressed the same.

The rest of your components are a different matter: running at higher fsb will increase the stress they operate under- and some don't like, in fact some will hardly tolerate ANY FSB over 133.

Most will go higher though, and some will run a LOT higher!

And that is why FSB Overclocks are preferred: the entire system is a lot faster.
Example: XP1700@1800 10x multi, 180mhz FSB and 360mhz memory bus speed (DDR)
Spec on the bus is 133, so the ram is meant to run at 266mhz.

A lot of memory bandwidth there, and I'd rather have that than cpu speed, for the most part. The memory needs a boost to keep up anyway!

Bus speeds are one of the biggest bottlenecks in pcs right now- large amounts of ram, cache and software tricks make hard drives keep up better, video is ahead of cpus, and so on: but all that data has to travel over the bus: the bigger the pipe, the faster the system will be.

Low multi's and the HIGHEST fsb you can get: only time to crank the multi up is if a component (including mobo) can't go any higher with FSB.

BTW: I kinda like FSB OC's

Actually you coulndt use 13x or above without modifing the XP. Their set up to run at 12.5x and below or 13x and above. I might modify my 1600's cause their stable 1.73 at default voltage so I could just make the default multi 13x.