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I've had this monitor for a few years, and it's been a pretty good workhorse.

A disassembly manual is linked: http://www.manualslib.com/manual/798421/Asus-Mw221u-201u.html#manual

Update: I reflowed the solder connections on the button/speaker PCB, and the issue with the buttons being unresponsive seems to be permanently resolved. I suspect it was manhandled a bit when it was moved across the country by freight shippers, and developed a fault in the solder connections.

The screen will go blank intermittently. There is no discernable pattern to this behavior. I think I've narrowed it down to the operating system. I can make the behavior occur pretty reliably by moving the mouse around quickly, moving the cursor to the bottom (causing the dock to 'unhide' and animate), or doing any action that changes a significant number of pixels on the screen (the main iMac screen or the monitor's screen, makes no difference).

Any insight into the problem would be appreciated. Is there something I've missed? Does anyone know anything about this 'OverDrive' Mode?

Thanks in advance.

When on Snow Leopard, I had no issues. My laptop on Lion doesn't seem to have the problem, but the iMac running Yosemite (where I really need the darned thing) seems to be having fits, and I suspect that Apple isn't in too much of a rush to get anything like it fixed.

Console:

1/1/16 4:57:23.000 PM kernel[0]: process WindowServer[161] caught causing excessive wakeups. Observed wakeups rate (per sec): 240; Maximum permitted wakeups rate (per sec): 150; Observation period: 300 seconds; Task lifetime number of wakeups: 644523

Console Messages when monitor is disconnected:

1/1/16 5:12:35.591 PM WindowServer[161]: Received display connect changed for display 0x4271b00

1/1/16 5:12:35.593 PM WindowServer[161]: Found 24 modes for display 0x04271b00 [24, 0]

1/1/16 5:12:35.629 PM WindowServer[161]: Received display connect changed for display 0x1a488dd1

1/1/16 5:12:35.629 PM WindowServer[161]: Found 1 modes for display 0x1a488dd1 [1, 0]

1/1/16 5:12:35.629 PM WindowServer[161]: Display 0x1a488dd1 changed state to offline

1/1/16 5:12:35.656 PM WindowServer[161]: Display 0x04271b00: GL mask 0x1; bounds (0, 0)[1920 x 1200], 24 modes available Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9c6c, S/N 0, Unit 0, Rotation 0 UUID 0x96293c70d3020ce8525b75ab1ea2c600, ColorSpace { -1462362547 } 1/1/16 5:12:35.656 PM WindowServer[161]: GLCompositor: GL renderer id 0x01021a02, GL mask 0x00000003, accelerator 0x000039a3, unit 0, caps QEX|MIPMAP, vram 256 MB texture max 8192, viewport max {8192, 8192}, extensions NPOT|GLSL|FLOAT

1/1/16 5:12:35.656 PM WindowServer[161]: Display 0x003f003d: GL mask 0x2; bounds (1920, 89)[1 x 1], 1 modes available off-line, enabled, OpenGL-accel, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0 UUID 0xffffffffffffffffffffffffffffffff, ColorSpace { 937663699 }

1/1/16 5:12:35.656 PM WindowServer[161]: GLCompositor: GL renderer id 0x01021a02, GL mask 0x00000003, accelerator 0x000039a3, unit 0, caps QEX|MIPMAP, vram 256 MB texture max 8192, viewport max {8192, 8192}, extensions NPOT|GLSL|FLOAT

1/1/16 5:12:35.720 PM WindowServer[161]: Display 0x04271b00: Unit 0: Startup Mode 1920 x 1200, CGSThirtytwoBitColor, Resolution 1, ioModeID 0x80007000, ioModeDepth 0x1, IOReturn 0x0

1/1/16 5:12:35.721 PM WindowServer[161]: CGXDisplaysDidReconfigure: Display added

1/1/16 5:12:35.721 PM WindowServer[161]: CGXDisplaysDidReconfigure: Display removed

1/1/16 5:12:35.727 PM WindowServer[161]: Display 0x04271b00: GL mask 0x1; bounds (0, 0)[1920 x 1200], 24 modes available Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9c6c, S/N 0, Unit 0, Rotation 0 UUID 0x96293c70d3020ce8525b75ab1ea2c600, ColorSpace { -1462362547 }

1/1/16 5:12:35.727 PM WindowServer[161]: GLCompositor: GL renderer id 0x01021a02, GL mask 0x00000003, accelerator 0x000039a3, unit 0, caps QEX|MIPMAP, vram 256 MB texture max 8192, viewport max {8192, 8192}, extensions NPOT|GLSL|FLOAT

1/1/16 5:12:35.727 PM WindowServer[161]: Display 0x003f003d: GL mask 0x2; bounds (2944, 89)[1 x 1], 1 modes available off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0 UUID 0xffffffffffffffffffffffffffffffff, ColorSpace { 937663699 }

Console messages occurring after display is connected:

1/1/16 5:19:10.663 PM com.apple.AmbientDisplayAgent[241]: AMBD Agent: xpc connection became invalid during event handler

1/1/16 5:19:10.663 PM com.apple.AmbientDisplayAgent[241]: AMBD Agent: xpc connection became invalid during event handler

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What is "Overdrive Mode" on an Asus monitor?

Overdrive is used to prevent ghosting on LCD displays.

Ghosting is a trailing motion artifact. It is caused by asymmetric pixel transitions: Transitions from between two colors can be faster in one direction than the other direction.


What is Overdrive For?

Without overdrive, LCD displays are prone to ghosting. Ghosting is typically caused by the asymmetric speeds of pixel transitions. LCD pixels often transition faster (or more completely) to a specific color, than back from a specific color. This creates the differences in motion artifacts on the leading edge versus the trailing edge of moving on-screen objects.

Overdrive speeds up the pixel transitions by using higher voltages on the pixels. This reduce ghosting. However, excess overdrive can create coronas. Coronas, also known as “overdrive artifacts”, or “inverse ghosting”, is caused by the pixel overshooting its final color value, and rippling (bouncing back) to its final color value.

Source LCD Motion Artifacts: Overdrive


Further Reading

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  • Great answer to the overdrive part of the question. Question updated to reflect progress with the problem.
    – Jeff H.
    Jan 1 '16 at 23:11

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