Turn a Radeon X1900 PC into a Mac-compatible RadeonX1900

A member of strangedogs forum has described the procedure to flash a Radeon X1900PC to make it Mac compatible.
The beauty of the trick: you do not need to solder any parts of the GPU, nor perform the flashing step in a PC, you simply need to boot a Mac Pro from ... DOS!
We have repeated the procedure with some changes, and indeed we could flash a Radeon X1900XTX (faster than the XT), via a modified firmware with Graphiccelerator. The graphic card is then clocked at 650MHz for the GPU and 750MHz for the RAM.
We will describe more in details the procedure in a near future in an article, but we can already mention that it requires a Radeon X1900XT or XTX with 512MB of GDDR RAM. Models featuring only 256MB of RAM will not work. In addition, this trick does not work with Radeon X1950XT or XTX.
So you need to get a Radeon X1900XT or XTX with 512MB of RAM; it is quite difficult as those models are EOL in Europe.
The price should be around 300 Euros for a XT model, and 100 Euros more for the faster XTX version.
PS: The firmware of graphic cards for PPC and MacIntel being so much different, it is impossible to flash a Radeon X1900 to make compatible with PMG5.