Ask ATI about it, and you'll be told there's no way to turn a Radeon X800 Pro into its higher-powered sibling, the Radeon X800 XT.
Ask a team of Russian hackers, however, and they'll say that, yes, it is possible to make the modification.
Their investigation of the GPUs appears to have revealed a single resistor on the XT package that's missing from the Pro. Reconnecting the two pins on the Pro chip, and copying an XT-based card's on-board firmware over to the Pro-based board seems to enable the four extra pixel pipelines active in the 16-pipeline XT but disabled in the 12-pipeline Pro.
Website DigitLife, for one, has tried the procedure and claims success. It also managed to overclock the Pro to XT levels: a 520MHz core and 1.12GHz memory.
Now, at ATI's UK X800 roll-out, company architecture specialist Raja Kuduri told The Register that each unused bank for four pipelines is physically fused after sorting, so punters shouldn't expect to be able to make such a mod. The Pro's core usually runs at 475MHz, its memory at 900MHz.
The question is, how common are XT chips masquerading as Pro parts? Only ATI can say, and the company isn't likely to divulge that information to the public - and probably not even their own customers.
The only way of finding out if a chip can be modified this way is by carrying out the mod. procedure and checking using an application like RivaTuner. Chances are, though, you're going to nuke your GPU - whatever it is - and as such we can't recommend the technique. If you want to risk fritzing your expensive graphics card, on your own head be it. ®