'wrong' frequencies used for 1920x1080 resolution

I connected PandaBoard to my 24" Samsung 2494HM monitor's HDMI input to check how it goes with FullHD resolution. It switched but my monitor was complaining that resolution is not optimal. I have to admit that screen was very far from optimal:

- left edge of printed screen was out of monitor
- letters were very hard to read

Monitor menu said:
- 67.5kHz 60Hz 1920x1080 for PandaBoard
- 66.4kHz 60Hz 1920x1080 for my ATI Radeon 5450 (open drivers)

EDID from my ATI card:

16:16 hrw@home:card0-DVI-I-1$ xxd edid
0000000: 00ff ffff ffff ff00 4c2d d404 3432 494b ........L-..42IK
0000010: 0a13 0103 8035 1e78 2a60 41a6 564a 9c25 .....5.x*`A.VJ.%
0000020: 1250 5423 0800 8100 8140 8180 9500 a940 .PT#.....@.....@
0000030: b300 0101 0101 1a36 80a0 7038 1f40 3020 .......6..p8.@0
0000040: 3500 132a 2100 001a 0000 00fd 0038 3c1e 5..*!........8<.
0000050: 5111 000a 2020 2020 2020 0000 00fc 0053 Q... .....S
0000060: 796e 634d 6173 7465 720a 2020 0000 00ff yncMaster. ....
0000070: 0048 3958 5333 3030 3335 380a 2020 00fe .H9XS300358. ..

EDID from PandaBoard:

root@linaro:/sys/class/drm/card0-HDMI-A-1# hexdump edid
0000000 ff00 ffff ffff 00ff 2d4c 04d5 0000 0000
0000010 130a 0301 1080 7809 602a a641 4a56 259c
0000020 5012 2354 0008 40a9 8081 4081 0081 0095
0000030 00b3 0101 0101 3a02 1880 3871 402d 2c58
0000040 0045 5aa0 0000 1e00 1d01 1880 1c71 2016
0000050 2c58 0025 5aa0 0000 9e00 0000 fd00 3200
0000060 1b3c 1151 0a00 2020 2020 2020 0000 fc00
0000070 5300 6e79 4d63 7361 6574 0a72 2020 d001
0000080 0302 f11c 9048 051f 0414 0313 2312 0709
0000090 8307 0001 6600 0c03 1000 8000 1d01 7200
00000a0 d051 201e 286e 0055 5aa0 0000 1e00 1d01
00000b0 bc00 d052 201e 28b8 4055 5aa0 0000 1e00
00000c0 0a8c 90d0 4020 2031 400c 0055 5aa0 0000
00000d0 1800 1d01 d080 1c72 2016 2c10 8025 5aa0
00000e0 0000 9e00 0a8c 8ad0 e020 102d 3e10 0096
00000f0 5aa0 0000 1800 0000 0000 0000 0000 0e00
0000100