Title 聽起來 nonsense แต่ actually recipe for weird problem encountered with desktop system custom-built PC with ASUS motherboard monitor made by Dell connected HDMI cable so far so good
Then system rebooted after months calm peaceful work during boot sequence following happened screen went sleep mode usual no signal from HDMI then didn't wake up right away didn't see BIOS splash (press F2) then LED on motherboard cycled color sequence red yellow white green nope no green white light stayed on
There are four lights!
Went online consulted motherboard manufacturer site including indication color code possible errors white LED on indicates: display connectivity problem well yes because can't get into BIOS however once boot sequence completes system works fine monitor wakes up can log into Windows etc
Problem seems partial in effect but several months beforehand plus several reboots no white light issues does this mean hardware thing? set about troubleshooting one cable at a time
DisplayPort versus HDMI
Dell monitor ships with DisplayPort cable (no HDMI) figured if this what vendor giveth let's see if affects situations changed cables rebooted poof white light gone blinked system check good green light sequence finished successfully
However still no BIOS monitor would not wake right moment show motherboard logo allow press F2 enter BIOS settings
Monitor drivers
Using different connection type solved half problem but issue monitor's so-called "deep sleep" remains decided try something else powered down system this time did get see BIOS menu but following ANOTHER reboot nope
Realized needed focus on Windows 10 how it handles power management after all when OS goes down sends bunch signals to connected hardware devices apparently something causes Dell monitor sleep then not wake up right moment
Checked device properties realized monitor wasn't recognized as Dell nope
Monitor behaving fine color calibration resolution refresh rate sleep all of it inside Windows no issues but categorized as generic device using standard Microsoft drivers figured let's see what happens if try official Dell drivers
Installed drivers power-cycled monitor (off, on) now Windows 10 device manager showing device correctly Dell U2719D excellent rebooted system entire sequence went smoothly lights did flash dance BIOS menu there all of it problem solved
สรุป
Article นี้ may not be relevant too many people but think message important had to solve problem manifested suddenly despite no system change problem doesn't really have "crippling" effect day-to-day usage problem seems mix two components hardware software never fun
In a way software quite fragile subtle differences among components near-identical setup can make huge amount difference could have system works perfectly then different system does funny things comes down to single cable or a driver mean okay but there ought to be more resilience
Anyway enough philosophy if your mobo lights blink on you and data points to connectivity problem try work way through methodically try isolate issue working through different setup permutations stick to defaults where possible because that's what vendors usually check certify hardware and make sure drivers configured correctly sounds trivial but not when one little light suddenly switches on starts annoying you hopefully this will be of use if not straight howto then generic practical pointer bye bye now
P.S. SMPTE color bars thumbnail used on homepage licensed under CC BY-SA 3.0
Cheers.
