[{"data":1,"prerenderedAt":343},["ShallowReactive",2],{"en-post-35":3},{"id":4,"title":5,"body":6,"description":16,"extension":336,"meta":337,"navigation":338,"path":339,"seo":340,"stem":341,"__hash__":342},"content/post/35.md","Screen Flickering, Vertical Lines or a Garbled Display: Monitor and Graphics Troubleshooting",{"type":7,"value":8,"toc":324},"minimark",[9,13,17,22,25,38,47,51,78,82,97,104,108,128,132,163,167,206,210,288,292,297,300,305,308,313,316,321],[10,11,5],"h1",{"id":12},"screen-flickering-vertical-lines-or-a-garbled-display-monitor-and-graphics-troubleshooting",[14,15,16],"p",{},"A screen that flickers, shows vertical or horizontal lines, turns garbled, or blinks to black and back is both annoying and worrying, because it looks like an expensive repair. Software causes account for most of these cases, covering cables, drivers and refresh rate, and only a minority genuinely need a new part. The decisive move is to work out whether the fault sits in the monitor or in the machine.",[18,19,21],"h2",{"id":20},"_1-run-the-split-test-first","1. Run the split test first",[14,23,24],{},"This is the step that stops you from buying a graphics card or a monitor you do not need. Connect the monitor to another computer or laptop, or connect a monitor you know is good to your machine.",[26,27,28,32,35],"ul",{},[29,30,31],"li",{},"Fine on another monitor means the original monitor or its cable is at fault.",[29,33,34],{},"Still flickering on another machine means the monitor or its cable is at fault.",[29,36,37],{},"Still flickering with both the cable and the monitor swapped means the problem is your graphics card or the machine itself, which is a driver or hardware matter.",[14,39,40,41,46],{},"A monitor that never lit up at all is a different path, covered in ",[42,43,45],"a",{"href":44},"/post/25/","External Monitor Not Detected in Windows 11",".",[18,48,50],{"id":49},"_2-cables-and-ports-where-most-cases-live","2. Cables and ports (where most cases live)",[26,52,53,60,66,72],{},[29,54,55,59],{},[56,57,58],"strong",{},"Reseat the plug."," A loose HDMI, DisplayPort or VGA plug, or oxidised pins, is the top cause of flicker. Pull both ends, push them back firmly, and tighten the screws or the latch on VGA and DisplayPort.",[29,61,62,65],{},[56,63,64],{},"Fit a better cable."," Cheap HDMI and DisplayPort cables are poorly shielded and flicker or snow badly at 4K and high refresh rates. Use a certified cable (HDMI 2.1, DisplayPort 1.4) and keep it under 2 to 3 metres.",[29,67,68,71],{},[56,69,70],{},"Use the right port."," With a discrete graphics card, plug into the card's video output. Plugging into the motherboard instead (the integrated graphics port) gives no signal or odd behaviour.",[29,73,74,77],{},[56,75,76],{},"Beware adapters."," Cheap HDMI to VGA or USB-C to HDMI adapters cause flicker frequently. Prefer a native port or a branded adapter.",[18,79,81],{"id":80},"_3-refresh-rate-and-resolution","3. Refresh rate and resolution",[83,84,85,88,91,94],"ol",{},[29,86,87],{},"Right-click the desktop > Display settings > Advanced display, and pick the monitor's native resolution and its recommended refresh rate, such as 60Hz or 144Hz.",[29,89,90],{},"A refresh rate above what the monitor supports produces a blinking black screen. Boot into Safe Mode, set it back to 60Hz, then raise it step by step until you find a stable value.",[29,92,93],{},"Mixing refresh rates across monitors, a 144Hz main screen with a 60Hz second one, occasionally makes everything flicker. Set a fixed refresh rate per display in the graphics control panel.",[29,95,96],{},"HDR on a basic cable or a basic panel also flickers or shifts colours. Go to Settings > System > Display and turn Use HDR off, then watch what happens.",[14,98,99,100,46],{},"Sharpness problems tied to resolution and scaling are a separate thread, covered in ",[42,101,103],{"href":102},"/post/22/","Blurry Text or Wrong Resolution in Windows",[18,105,107],{"id":106},"_4-graphics-driver","4. Graphics driver",[26,109,110,116,122],{},[29,111,112,115],{},[56,113,114],{},"Clean reinstall."," In Device Manager > Display adapters, right-click the discrete GPU > Uninstall device (tick the box to delete the driver) and restart. For a thorough job, use DDU (Display Driver Uninstaller) in Safe Mode, then install the latest stable release from NVIDIA, AMD or Intel. Avoid driver utility bundles.",[29,117,118,121],{},[56,119,120],{},"Roll back."," If flickering started right after a driver update, go to Device Manager > Display adapters > right-click > Properties > Driver > Roll Back Driver.",[29,123,124,127],{},[56,125,126],{},"Reset driver settings."," In NVIDIA Control Panel or AMD Adrenalin, restore image settings to default and turn off experimental options such as fast vertical sync and overclocking.",[18,129,131],{"id":130},"_5-hardware-and-temperature","5. Hardware and temperature",[26,133,134,145,151,157],{},[29,135,136,139,140,144],{},[56,137,138],{},"Clean the dust and bring temperatures down."," An overheating GPU or CPU causes garbling and driver resets, which is very common on laptops. ",[42,141,143],{"href":142},"/post/24/","Computer Overheating and a Fan Running Constantly"," covers how to do it.",[29,146,147,150],{},[56,148,149],{},"Power and overclocking."," An overclocked card garbles easily, so return clocks to stock. A power connector that is not fully seated also causes black screens and flicker.",[29,152,153,156],{},[56,154,155],{},"GPU solder joints on older laptops."," Repeated heat cycles can crack the BGA joints under the GPU, which shows as intermittent garbling that slowly gets worse. That needs a reflow or reballing at a repair shop.",[29,158,159,162],{},[56,160,161],{},"An ageing monitor."," Vertical lines in a fixed position, uneven brightness and edge bleed on a monitor that has seen years of use point to the panel or the driver board, where replacing beats repairing.",[18,164,166],{"id":165},"_6-system-and-other-software","6. System and other software",[26,168,169,175,181,192],{},[29,170,171,174],{},[56,172,173],{},"Turn off transparency and animations."," In Settings > Accessibility > Visual effects, switch off transparency effects and animation effects. Some older machines with integrated graphics stop flickering once you do.",[29,176,177,180],{},[56,178,179],{},"Magnetic interference."," Phones, strongly magnetised speakers and high-power appliances near the monitor make the picture shake.",[29,182,183,186,187,191],{},[56,184,185],{},"Conflicting multi-display modes."," Press ",[188,189,190],"code",{},"Win+P"," and try Second screen only or Extend, to rule out the two displays fighting over the signal.",[29,193,194,197,198,201,202,205],{},[56,195,196],{},"System file repair."," If you suspect the Desktop Window Manager (dwm) is crashing and causing flicker, run ",[188,199,200],{},"sfc /scannow"," and ",[188,203,204],{},"DISM /Online /Cleanup-Image /RestoreHealth"," in an admin terminal.",[18,207,209],{"id":208},"_7-quick-reference-by-symptom","7. Quick reference by symptom",[211,212,213,229],"table",{},[214,215,216],"thead",{},[217,218,219,223,226],"tr",{},[220,221,222],"th",{},"Symptom",[220,224,225],{},"Suspect first",[220,227,228],{},"First move",[230,231,232,244,255,266,277],"tbody",{},[217,233,234,238,241],{},[235,236,237],"td",{},"Flashes once and recovers, at random",[235,239,240],{},"Loose plug, poor contact, interference",[235,242,243],{},"Reseat, swap the cable",[217,245,246,249,252],{},[235,247,248],{},"Vertical or horizontal line in a fixed spot",[235,250,251],{},"Panel or cable damage",[235,253,254],{},"Split test",[217,256,257,260,263],{},[235,258,259],{},"Garbled output plus game crashes",[235,261,262],{},"Driver, overclock, heat",[235,264,265],{},"Clean reinstall, cool it down",[217,267,268,271,274],{},[235,269,270],{},"Blinking black screen with a signal present",[235,272,273],{},"Refresh rate, HDR, cable",[235,275,276],{},"Safe Mode, set 60Hz",[217,278,279,282,285],{},[235,280,281],{},"One of several displays flickers",[235,283,284],{},"Mixed refresh rates, port",[235,286,287],{},"Fix a rate per display",[18,289,291],{"id":290},"common-questions","Common questions",[14,293,294],{},[56,295,296],{},"Does a flickering screen mean my graphics card is failing?",[14,298,299],{},"Usually not. Run the split test first. Only flicker that survives a new cable and a new monitor points at the card, and among card problems the driver and heat account for most of them. Genuine hardware failure is a small share.",[14,301,302],{},[56,303,304],{},"Why does it only flicker in games and not on the desktop?",[14,306,307],{},"Games push the GPU to full load and switch refresh rates, which is when a cable with too little bandwidth, unstable power, an overclock or excess heat finally shows. Drop to 60Hz to confirm, then deal with cooling.",[14,309,310],{},[56,311,312],{},"I fitted a new cable and it still flickers. What next?",[14,314,315],{},"Follow section 3 and drop to 60Hz with HDR off. If it still flickers, do a clean driver reinstall, and only then think about hardware.",[14,317,318],{},[56,319,320],{},"The external monitor flickers but the laptop's own screen is fine. Where is the fault?",[14,322,323],{},"It is in the external cable and port. Swap the cable first, then move to a different video output, and finally check whether you are plugged into the integrated graphics port.",{"title":325,"searchDepth":326,"depth":326,"links":327},"",2,[328,329,330,331,332,333,334,335],{"id":20,"depth":326,"text":21},{"id":49,"depth":326,"text":50},{"id":80,"depth":326,"text":81},{"id":106,"depth":326,"text":107},{"id":130,"depth":326,"text":131},{"id":165,"depth":326,"text":166},{"id":208,"depth":326,"text":209},{"id":290,"depth":326,"text":291},"md",{},true,"/post/35",{"title":5,"description":16},"post/35","zIb5WN2PrXQNcQG9rzl_BGVWbAPrmMaLfQc7LQ4_z_I",1794378303926]