I'm guessing, none?

Both CPUs are pretty much an overkill for any DOS game, you'll be fine with a Celeron. Sorry to hear about what happened to your K6, though

Well for dos which is better the 810 or the rage ii, I know they are both terrible cards but which is less terrible

Again, both are complete overkill. The i810 (or rather its integrated i752) is far more powerful, but because it shares system RAM bandwidth with the CPU it pulls all performance down with it. The Rage II is old, but still very much Windows-era, so far in excess of what is required for DOS. Note that some rare i810 systems had 4MB of dedicated framebuffer RAM onboard. In that case, system RAM bandwidth isn't affected anywhere near as much and performance is much better. Check which you have.

But again, with Dune2 your biggest problem will be running too fast regardless of the video card.

In terms of CPU, the Celeron will clearly be faster in FPU-dependent games such as Quake. In ALU-dependent games (almost all other DOS titles), the K6-3 would have been faster, but not hugely so. Note that a Celeron 400 generally overclocks quite well and should run OK at 500MHz if your motherboard can do 83MHz FSB. That would make it more than a match for the K6-3 450.

Alright, and for dune II I was down clocking on the k6 not sure how to down clock the celly the k6 board had bios fsb controls

The Rage II is essentially a Mach 64 2D core. It's a great card for DOS stuff.