Let's don't confuse the guy, tcman, an X850Pro is more than powerful enough for CS 1.6 (heck, a GF4 MX would do just fine), so there is no need to resort to unlocking the pipelines (it may improve things a bit if all goes well and the locked pipelines are not defective, but the card should run this game without any problem and has done so in the past, so it's not the issue we're dealing with, plus it could add new problems).
That said, I am running out of ideas.
No heavy processes in the background? No warning signs in Device Manager? The PSU can cause all sorts of issues, but if it worked fine before the format, then I guess that's not it.