If you expect top performance from your system, you have to accept that it all starts and ends with the CPU. Whiz-bang graphics cards and oceans of RAM won't fix a system that's dragged down by a pokey processor. Wether you'ew crunching numbers or rendering dimly lit hallways in Quake, the capability of your system to get the job done relies first and foremost on its CPU.
The AMD K5 has been coming slowly, but now it's there and getting better and better. By now, you can get it from a PR 75 up to a PR 166. It's FPU is still slower than the FPU of the Pentium, but it's better than the FPU of the 6x86. It also will soon be released as a split voltage version, which will reduce heat problems of this CPU as well.
Here a table to show the weird CPU speed/bus speed/multiplier relations of the K5 CPUs:
|Processor Performance||Clock Speed
|PCI Bus Speed
|K5 PR 90||90||60||30||1.5|
|K5 PR 100||100||66||33||1.5|
|K5 PR 120||90||60||30||1.5|
|K5 PR 166||116.66||66||33||1.75|
As you can see, the PR120 runs at the same speed as the PR90, the PR100 runs at the same speed as the PR133. These CPUs obviously have got a different die. The PR120 and PR133 are more advanced than the PR90/100. This however only touches the integer performance. The FPU performance of the PR133 is the same as of the PR100.
Due to these strange multiplier settings, the K5 has got a fixed multiplier, which cannot be changed from out side via multiplier jumpers. The PR75 to PR133 will run at 1.5 multiplier regardless what the jumpers say, the PR166 will also always run at x1.75.