The the X1900XT and X1950XT, are pretty close, with the X1950XT winning slightly. Isn't the X1950 series, just a revision of the X1900 series?
at tomshardware in the benchies (yet they aren't accurate) they have the same, or the 1950 beats it by about 5fps at THE MOST. and those are the 256 mb version. i have the 512 version.