Monitor no signal after start up

Are you getting post beeps on startup ? If not you may be dealing with a power issue . Just because your fans are running and your motherboard light comes on doesn't mean you have enough power in the power supply to run the machine .Power supplies can die slowly and still appear ok .If you have access to another power supply try changing it out . You may also want to try a different monitor or test your old monitor on another computer. depending on your motherboard you could try resetting the mem button common on Asus boards. Also you mentioned you've disconnected the power and that you've held down the power button for extended periods . Did you do this together? if not try unplugging from power and holding the power button down for roughly 60sec then plugging in and rebooting. Finally as dumb as this is going to sound but it happens to the best of us... is your monitor turned on and plugged in? Just sayin Hope something here helps and good luck

"This is the first time I've ever decided to post a piece of advice to any website/message board because I think it would really help a lot of people. I had the exactly same problem after installing a new motherboard. I tried everything I could think of and all the tips I found online; to list just a few: updating my BIOS, reinstalling Windows 10, changing from DP cable to HDMI, reinstalling all my drivers, reinstalling just graphics drivers, plugging and unplugging my Nvidia graphics card several times, cleaning/vacuuming every single component (my comp is as clean as a whistle - looks brand new, trying all kinds of combinations in BIOS settings, etc - nothing worked.

 

And here is how I SOLVED IT! After reading some unrelated advice about the ""turn on fast start-up"" function in Windows 10 and reading about how it can cause certain booting problems, I thought I might as well give it a try, nothing left to lose. So, I went to Control Panel/Power Options and under ""change setting that are currently unavailable"" turned off the fast start-up. Voila, problem solved! I'm guessing there is was kind of incompatibility between my motherboard (Intel Desktop Board DQ77MK) and this particular Windows setting. After spending a week dealing with this issue and going out of my ever-loving mind, you can imagine my relief. I'll make sure to post this advice on as many message boards I can to help other miserable souls like myself."

If your motherboard has an onboard graphics card you might want to try unplugging your PCI-E graphics card and plugging a monitor into the onboard graphics card. This will verify whether or not it is your PCI-E graphics card that is faulty or not.

"I get the some problem and tried all this metods, but don't work.

I talk with my techers and they tell me to remove the PCI graphic card, clean the contacts, with an ruber and a brush (with soft bristles), and put that again, and now are working normally."

Had the same problem and it ended up being a bad memory stick. Try removing the memory and see if you get the error beeps. If so then try one stick at a time and see if that solves the problem.

Tried everything except replacing parts , then solved the problem by vacuuming the air vents and then took off the lid and vacuumed the fan area and memory sticks . No issues for weeks now.