I think I mentioned it earlier. But the motherboard i was using had USWC enabled. ( by default, btw) it made a 50% performance difference in doom/quake.
Also, none of these benchmarks can even see the 2nd cpu. You'd have to be running some flavor of NT/2000/Linux AND a program that was multi threaded. When it comes to gaming on old systems, multi cpu is just for dick waving.
Also, there are major differences between chipsets and manufacturers. My ASUS P65UP5/8 motherboard FLYS with overdrive chips. But my Tyan boards are as buggy as a discount hooker.
It is a mistake to think you can solve any major problems just with potatoes.