IIO, I have to apologize, I confused you with GaryN who stated "what the guy did". I just thought there is more information around, or I didn't get it from the video as my english is not the best, or there is a "known" hardware hack out there. But it is up to Gary to answer why he knows "what the guy did"
not you! Sorry again.
The card was originally a 2 x 1.25Ghz. What you missed is "the guy" "Hurd" who modified it described the build on the Mac 68kMLA Forum
https://68kmla.org/bb/index.phpalthough I took a quick look and can't seem to find it…
Even so, in the YT video, the card is clearly shown and described to be changed to two 7448 procs, which is basically what Sonnet did to create the MDX 2 x 1.8Ghz that I have.
Although I have heard of others clocking the 7448 at 2Ghz (and possibly beyond), I have never tried for a few reasons:* In OS9
any proc running old Mac apps at 1Ghz or beyond feels like witchcraft anyway with windows flying open almost instantaneously and things that used to take time are now accomplished seemingly in seconds.
* In the Ghz range, you start to bump up against other limitations of the old OS such as only one proc used, but more importantly, the app designs themselves were created around the capabilities of the original PPC hardware running in the 400Mhz range with limited RAM as well. So, it
feels as though data is processed in smaller chunks for the sake of reliability and such. Remember, old Mac OS developers lived in constant fear of releasing an app that would crash because that would usually crash the entire machine as well. With updates distributed on hard media that had to be burnt and snail-mailed, that could easily turn one's app into a pariah that no one wanted very quickly and it was welcome to bankruptcy court…
* In OSX, although 2 x 2Ghz
can create a speed improvement in processor-heavy tasks like recalculating spreadsheets, processing Photoshop images and such, only those who insist on using "ancient" software to do large amounts of serious work see any real benefits.
* Sonnet chose 1.8Ghz as the "sweet spot" where the 7448 is at optimum balance of speed vs. temperature. Indeed, my Sonnet CPUs ran cooler right out of the box that the 1.42Ghz ones they replaced. It's just a better proc, period.
* Sadly, the common things like websurfing and watching cat videos are still impossible to do without extreme difficulty due to other things than CPU speed. The miraculous convergence of lots of old audio and MIDI hardware and software turned into abandonware, which is capable of creating state-of-the-art-sounding results, which led to the creation of this Forum to begin with, is still by far the best reason to use this vintage stuff.