@Lightman, tested the GTX-650 and it is PCIe3x16 and works without problems with an 105MHz BCLK. Firmware from Bios update via Internet worked as an charm.

Trying the v2.7 Bios here, but no 4.7GHz in reach, still hitting the same wall at 4.6GHz and still seeing high Radeon temps. The cTDP option has disappeard completely in this version.