66MHz PCI in PCI PowerMacs?

[Mike Richardson]

And for all the effort you are going to go through hacking the bus up to 64-66mhz, you might as well spend a few bucks and just get a newer machine like a Sawtooth, which are cheap as heck right now.

He said the point was to just experiment and stuff. Of course if you really want more true speed the best way to go is a newer Mac, but the architecture of 7xxx Macs has proven remarkably upgradable. Who would of thought you could drop in 1 GHz CPUs and a gig of RAM and huge hard drives and fast video cards? Most PCs can't do that.

 

[OtakuMegane]

Did you ever try the hack on a machine with dual PCI busses? Does it like having a 66MHz bus and a 33MHz bus?

I did all this in a Power Tower Pro. Both buses are clocked by one oscillator, so it was dual 66MHz PCI. If one could be kept at 33MHz the hack would be more practical since you could use all the normal cards in one of the buses.

Of course if you really want more true speed the best way to go is a newer Mac, but the architecture of 7xxx Macs has proven remarkably upgradable. Who would of thought you could drop in 1 GHz CPUs and a gig of RAM and huge hard drives and fast video cards? Most PCs can't do that.

Exactly the reason I started that project. The final Tsunami architecture from the PCI family especially was nicely overengineered. I did normal upgrading until I hit the limits of what was available, then remembered someone mentioned on the OWC forums about overclocking the PCI to 40MHz to deal with the old ATA stutering problem. Decided to try it and sure enough it functioned. Then I got the idea, why not throw in a higher speed and see what happens? Tried a 50MHz first, made the video card unstable at first but it booted. So then I try the 66MHz and wow, it worked. 8-o Everything proceeded from that point.