re -installed linux mint , same problem
one screen can handle the 2560*1440 definition
the second one , on the hdmi can't !!
take a look plz :
root@guillaume-U800:~# xrandr --prop
Screen 0: minimum 320 x 200, current 4480 x 1440, maximum 8192 x 8192
DP-1 connected 1920x1080+2560+360 (normal left inverted right x axis y axis) 725mm x 428mm
EDID:
00ffffffffffff0005e379329ddb0000
031e010380492b782a79e5ac5144ac26
0f5054bfef00d1c0b300950081808140
81c001010101565e00a0a0a029503020
3500d5ac2100001ea073006aa0a02950
08203500d5ac2100001a000000fd0030
4c1e721e000a202020202020000000fc
005133323739574735420a202020015a
020329f14b101f051404130312021101
230907078301000067030c001000383c
681a00000101304c00023a801871382d
40582c4500d5ac2100001e8c0ad08a20
e02d10103e9600d5ac210000188c0ad0
90204031200c405500d5ac21000018f0
3c00d051a0355060883a00d5ac210000
1c0000000000000000000000000000c4
Content Protection: Undesired
supported: Undesired, Desired, Enabled
max bpc: 12
range: (6, 12)
Broadcast RGB: Automatic
supported: Automatic, Full, Limited 16:235
audio: auto
supported: force-dvi, off, auto, on
link-status: Good
supported: Good, Bad
CONNECTOR_ID: 85
supported: 85
non-desktop: 0
range: (0, 1)
2560x1440 59.95 + 74.97
1920x1080 60.00* 60.00 50.00 59.94
1920x1080i 60.00 50.00 59.94
1280x1440 59.91
1680x1050 59.88
1280x1024 75.02 60.02
1440x900 59.90
1280x960 60.00
1280x720 60.00 60.00 50.00 59.94
1024x768 75.03 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
720x576 50.00 50.00 50.00
720x480 60.00 60.00 59.94 59.94 59.94
640x480 75.00 72.81 66.67 60.00 59.94 59.94
720x400 70.08
DP-2 connected primary 2560x1440+0+0 (normal left inverted right x axis y axis) 725mm x 428mm
EDID:
00ffffffffffff0005e37932dedc0000
031e0104b5492b783b79e5ac5144ac26
0f5054bfef00d1c0b300950081808140
81c001010101565e00a0a0a029503020
3500d5ac2100001ea073006aa0a02950
08203500d5ac2100001a000000fd0030
4c72721e010a202020202020000000fc
005133323739574735420a202020017c
020318f14b0103051404131f12021190
2309070783010000023a801871382d40
582c4500d5ac2100001e011d007251d0
1e206e285500d5ac2100001e8c0ad08a
20e02d10103e9600d5ac210000188c0a
d090204031200c405500d5ac21000018
f03c00d051a0355060883a00d5ac2100
001c00000000000000000000000000b5
Content Protection: Undesired
supported: Undesired, Desired, Enabled
max bpc: 12
range: (6, 12)
Broadcast RGB: Automatic
supported: Automatic, Full, Limited 16:235
audio: auto
supported: force-dvi, off, auto, on
link-status: Good
supported: Good, Bad
CONNECTOR_ID: 94
supported: 94
non-desktop: 0
range: (0, 1)
2560x1440 59.95*+ 74.97
1920x1080 60.00 60.00 50.00 59.94
1920x1080i 60.00 50.00 59.94
1280x1440 59.91
1680x1050 59.95
1280x1024 75.02 60.02
1440x900 59.89
1280x960 60.00
1280x720 60.00 60.00 50.00 59.94
1024x768 75.03 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
720x576 50.00 50.00 50.00
720x480 60.00 60.00 59.94 59.94 59.94
640x480 75.00 72.81 66.67 60.00 59.94 59.94
720x400 70.08
HDMI-1 disconnected (normal left inverted right x axis y axis)
Content Protection: Undesired
supported: Undesired, Desired, Enabled
max bpc: 12
range: (8, 12)
content type: No Data
supported: No Data, Graphics, Photo, Cinema, Game
aspect ratio: Automatic
supported: Automatic, 4:3, 16:9
Broadcast RGB: Automatic
supported: Automatic, Full, Limited 16:235
audio: auto
supported: force-dvi, off, auto, on
link-status: Good
supported: Good, Bad
CONNECTOR_ID: 100
supported: 100
non-desktop: 0
range: (0, 1)