IMac – External display randomly acquires and loses signal under Mavericks 10.9.4

I am trying to use a Planar PXL2790MW external display with my iMac 11,3 (2.93 GHz 27inch) connected by a Mini DisplayPort to DisplayPort cable.

The display works intermittently: at random times, it will acquire signal from the computer and then drop it again after anywhere from ten minutes to half an hour. It will report no signal for various lengths of time before briefly coming back on again. Restarting the computer and turning the monitor on and off (in any order) seems to make no difference to whether or not the signal is sent. It seems quite random.

The same thing happens both under BootCamp (Win7) and OSX (10.9.4) When the display does have signal, it performs perfectly. During one of the intervals when it was working, I tried to move the cable about vigorously including at the ports, to see if that's the problem; it didn't seem to make a difference.

I have tried zapping the PRAM and resetting the SMC, to no effect. I have tried detecting the display in Windows when it goes off, also to no effect.

Edit: I append the Console log for one of these events (a particularly brief one, the monitor is usually lucid for many minutes). The external display, as we can see, is 0x3f003d. It comes on, then eventually state-changes to offline – for no reason that I can discern.

31-07-14 1:03:27.025 PM WindowServer[353]: Received display connect changed for display 0x3f003d
31-07-14 1:03:27.027 PM WindowServer[353]: Found 111 modes for display 0x003f003d [111, 0]
31-07-14 1:03:27.028 PM WindowServer[353]: Display 0x003f003d changed state to online
31-07-14 1:03:27.067 PM WindowServer[353]: MPServiceForDisplayDevice: Invalid device alias (0)
31-07-14 1:03:27.067 PM WindowServer[353]: Display 0x042735c0: GL mask 0x1; bounds (0, 0)[2560 x 1440], 39 modes available
Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9cd7, S/N 0, Unit 0, Rotation 0
UUID 0x07570d0f8b9838d9f3b53e817caa82d0, ColorProfile { 2, "iMac"}
31-07-14 1:03:27.067 PM WindowServer[353]: GLCompositor: GL renderer id 0x01021b02, GL mask 0x00000003, accelerator 0x00003497, unit 0, caps QEX|MIPMAP, vram 1024 MB
texture max 16384, viewport max {16384, 16384}, extensions FPRG|NPOT|GLSL|FLOAT
31-07-14 1:03:27.067 PM WindowServer[353]: Display 0x6389e401: GL mask 0x2; bounds (2560, 0)[2560 x 1440], 111 modes available
Active, on-line, enabled, Vendor 418e, Model 2790, S/N 0, Unit 1, Rotation 0
UUID 0x4a237812254738fc40d33f9aa4c0eff8
31-07-14 1:03:27.068 PM Dock[811]: Set a breakpoint at CGSLogError to catch errors as they are logged.
31-07-14 1:03:27.068 PM Dock[811]: CGSCopyDisplayUUID: Invalid display 0x6389e401
31-07-14 1:03:27.068 PM Dock[811]: uuid_callback_master: failed to retrieve UUID for display 0x6389e401 (1001) (invariant failure)
31-07-14 1:03:27.068 PM Dock[811]: CGSCopyDisplayUUID: Invalid display 0x6389e401
31-07-14 1:03:27.069 PM Dock[811]: uuid_callback_master: failed to retrieve UUID for display 0x6389e401 (1001) (invariant failure)
31-07-14 1:03:27.079 PM WindowServer[353]: Display 0x042735c0: Unit 0: Startup Mode 2560 x 1440, CGSThirtytwoBitColor, Resolution 1, ioModeID 0x43e, ioModeDepth 0x1, IOReturn 0x0
31-07-14 1:03:27.080 PM WindowServer[353]: Display 0x6389e401: Unit 1: Startup Mode 2560 x 1440, CGSThirtytwoBitColor, Resolution 1, ioModeID 0x43e, ioModeDepth 0x1, IOReturn 0x0
31-07-14 1:03:27.080 PM WindowServer[353]: Display added
31-07-14 1:03:27.080 PM WindowServer[353]: Display removed
31-07-14 1:03:27.083 PM WindowServer[353]: Display 0x042735c0: GL mask 0x1; bounds (0, 0)[2560 x 1440], 39 modes available
Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9cd7, S/N 0, Unit 0, Rotation 0
UUID 0x07570d0f8b9838d9f3b53e817caa82d0, ColorProfile { 2, "iMac"}
31-07-14 1:03:27.083 PM WindowServer[353]: GLCompositor: GL renderer id 0x01021b02, GL mask 0x00000003, accelerator 0x00003497, unit 0, caps QEX|MIPMAP, vram 1024 MB
texture max 16384, viewport max {16384, 16384}, extensions FPRG|NPOT|GLSL|FLOAT
31-07-14 1:03:27.083 PM WindowServer[353]: Display 0x6389e401: GL mask 0x2; bounds (2560, 77)[2560 x 1440], 111 modes available
Active, on-line, enabled, Vendor 418e, Model 2790, S/N 0, Unit 1, Rotation 0
UUID 0x4a237812254738fc40d33f9aa4c0eff8
31-07-14 1:03:27.083 PM WindowServer[353]: _CGXGLDisplayContextForDisplayDevice: acquired display context (0x7fc1d2f05580) - enabling OpenGL
31-07-14 1:03:27.083 PM WindowServer[353]: GLCompositor: GL renderer id 0x01021b02, GL mask 0x00000003, accelerator 0x00003497, unit 0, caps QEX|MIPMAP, vram 1024 MB
texture max 16384, viewport max {16384, 16384}, extensions FPRG|NPOT|GLSL|FLOAT
31-07-14 1:03:27.134 PM WindowServer[353]: MPAccessSurfaceForDisplayDevice: Set up page flip mode on display 0x042735c0 device: 0x7fc1d2f015f0 isBackBuffered: 1 numComp: 3 numDisp: 3
31-07-14 1:03:27.148 PM WindowServer[353]: MPAccessSurfaceForDisplayDevice: Set up page flip mode on display 0x6389e401 device: 0x7fc1d2f05580 isBackBuffered: 1 numComp: 3 numDisp: 3
31-07-14 1:03:29.074 PM WindowServer[353]: Display 0x042735c0: Unit 0; ColorProfile { 2, "iMac"}; TransferTable (256, 3)
31-07-14 1:03:29.076 PM WindowServer[353]: Display 0x6389e401: Unit 1; ColorProfile { 4, "PXL2790MW"}; TransferFormula (1.000000, 1.000000, 1.000000)
31-07-14 1:03:29.118 PM WindowServer[353]: Display 0x042735c0: Unit 0; ColorProfile { 2, "iMac"}; TransferTable (256, 3)
31-07-14 1:03:29.119 PM WindowServer[353]: Display 0x6389e401: Unit 1; ColorProfile { 4, "PXL2790MW"}; TransferFormula (1.000000, 1.000000, 1.000000)
31-07-14 1:03:29.149 PM WindowServer[353]: Display 0x042735c0: Unit 0; ColorProfile { 2, "iMac"}; TransferTable (256, 3)
31-07-14 1:03:29.150 PM WindowServer[353]: Display 0x6389e401: Unit 1; ColorProfile { 4, "PXL2790MW"}; TransferFormula (1.000000, 1.000000, 1.000000)
31-07-14 1:03:29.162 PM WindowServer[353]: Display 0x042735c0: Unit 0; ColorProfile { 2, "iMac"}; TransferTable (256, 3)
31-07-14 1:03:29.163 PM WindowServer[353]: Display 0x6389e401: Unit 1; ColorProfile { 4, "PXL2790MW"}; TransferFormula (1.000000, 1.000000, 1.000000)
31-07-14 1:03:29.174 PM WindowServer[353]: Display 0x042735c0: Unit 0; ColorProfile { 2, "iMac"}; TransferTable (256, 3)
31-07-14 1:03:29.175 PM WindowServer[353]: Display 0x6389e401: Unit 1; ColorProfile { 4, "PXL2790MW"}; TransferFormula (1.000000, 1.000000, 1.000000)
31-07-14 1:03:29.192 PM WindowServer[353]: Display 0x042735c0: Unit 0; ColorProfile { 2, "iMac"}; TransferTable (256, 3)
31-07-14 1:03:29.193 PM WindowServer[353]: Display 0x6389e401: Unit 1; ColorProfile { 4, "PXL2790MW"}; TransferFormula (1.000000, 1.000000, 1.000000)
31-07-14 1:04:05.537 PM WindowServer[353]: Received display connect changed for display 0x42735c0
31-07-14 1:04:05.539 PM WindowServer[353]: Found 39 modes for display 0x042735c0 [39, 0]
31-07-14 1:04:05.541 PM WindowServer[353]: Received display connect changed for display 0x6389e401
31-07-14 1:04:05.541 PM WindowServer[353]: Found 1 modes for display 0x6389e401 [1, 0]
31-07-14 1:04:05.541 PM WindowServer[353]: Display 0x6389e401 changed state to offline
31-07-14 1:04:05.564 PM WindowServer[353]: Display 0x042735c0: GL mask 0x1; bounds (0, 0)[2560 x 1440], 39 modes available
Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9cd7, S/N 0, Unit 0, Rotation 0
UUID 0x07570d0f8b9838d9f3b53e817caa82d0, ColorProfile { 2, "iMac"}
31-07-14 1:04:05.564 PM WindowServer[353]: GLCompositor: GL renderer id 0x01021b02, GL mask 0x00000003, accelerator 0x00003497, unit 0, caps QEX|MIPMAP, vram 1024 MB
texture max 16384, viewport max {16384, 16384}, extensions FPRG|NPOT|GLSL|FLOAT
31-07-14 1:04:05.564 PM WindowServer[353]: Display 0x003f003d: GL mask 0x2; bounds (2560, 77)[1 x 1], 1 modes available
off-line, enabled, OpenGL-accel, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0
UUID 0xffffffffffffffffffffffffffffffff, ColorProfile { 4, "PXL2790MW"}
31-07-14 1:04:05.564 PM WindowServer[353]: GLCompositor: GL renderer id 0x01021b02, GL mask 0x00000003, accelerator 0x00003497, unit 0, caps QEX|MIPMAP, vram 1024 MB
texture max 16384, viewport max {16384, 16384}, extensions FPRG|NPOT|GLSL|FLOAT
31-07-14 1:04:05.584 PM WindowServer[353]: Display 0x042735c0: Unit 0: Startup Mode 2560 x 1440, CGSThirtytwoBitColor, Resolution 1, ioModeID 0x43e, ioModeDepth 0x1, IOReturn 0x0
31-07-14 1:04:05.584 PM WindowServer[353]: Display added
31-07-14 1:04:05.584 PM WindowServer[353]: Display removed
31-07-14 1:04:05.587 PM WindowServer[353]: Display 0x042735c0: GL mask 0x1; bounds (0, 0)[2560 x 1440], 39 modes available
Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9cd7, S/N 0, Unit 0, Rotation 0
UUID 0x07570d0f8b9838d9f3b53e817caa82d0, ColorProfile { 2, "iMac"}
31-07-14 1:04:05.587 PM WindowServer[353]: GLCompositor: GL renderer id 0x01021b02, GL mask 0x00000003, accelerator 0x00003497, unit 0, caps QEX|MIPMAP, vram 1024 MB
texture max 16384, viewport max {16384, 16384}, extensions FPRG|NPOT|GLSL|FLOAT
31-07-14 1:04:05.587 PM WindowServer[353]: Display 0x003f003d: GL mask 0x2; bounds (3584, 77)[1 x 1], 1 modes available
off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0
UUID 0xffffffffffffffffffffffffffffffff, ColorProfile { 4, "PXL2790MW"}
31-07-14 1:04:05.590 PM ControlCenter[1212]: Set a breakpoint at CGSLogError to catch errors as they are logged.
31-07-14 1:04:05.590 PM ControlCenter[1212]: CGSCopyDisplayUUID: Invalid display 0x6389e401