Unless you have a goldfinger device, or special athlon overclocking (or underclocking) devices, you are stuck to lowering the FSB. I wouldn't mess around with it too much, you would throw off the entire computer WAY too much if you lowered it. If you could lower the muliplier manually, either via jumpers or dipswitches, you could set the multiplier as low as 100Mhz (100FSB times 1 for multiplier). That would be terribly slow however =/ I had mechwarrior a while ago, and it worked fine on my computer. I think you just need to switch the settins somehow =/ Oldie, but goodie
I dont remember what it was called or where it was but there are a few DOS programs that take care of just that problem. I remember some space shooter games I used to play on a 386 that were imposible to play on my pentium 90 but that software worked for me. BTW your problem is the same reason computers had those old turbo switches several years ago.