On one system I get:
state 0x12000a [HDMI DMT (35) RGB full 5:4], 1280x1024 @ 60.00Hz, progressive
This is with a VGA monitor connected to HDMI via an adaptor, and config.txt modified to force this state.
The last 2 are just for my particular monitor
I seem to remember that I had a CEA mode at one stage, and things didn't work
HTH - sorry, but I've been away for a week