No Display when booting 9/10 times

hey,

for a while i have been having the following problem:
when i boot my PC, at least 9 out of 10 times i will get no display on my monitor. fans will be running. no POST beeps.

after a few (or more) tries it will eventually boot corectly and my monitor gets a signal and everything is fine.
the computer will then run for hours w/o any problems until i shut it down. next day when i try to boot same thing happens again.

i noticed that whenever i get no signal, a small red LED in front of my PC will NOT light up. then, after turning it off and on again multiple times, eventually the red LED will light up, i get a display on my monitor and everything is fine. no idea what that LED is, i am guessing its from my harddrive? if the PC boots correctly, that LED will blink continuously at different intervals. not sure if it always did this or if it used to be always ON instead of blinking, before all this started.

when this first happened i tried removing my 2 RAM sticks. i got 3 POST beeps. so i put them back in and would get no display. i tried them separately and would eventually get a signal and a normal boot. since then i am using only one of the 2. not sure what happens if i put them both in again.

i also tried to reset my bios using the jumper thing on my MB. by doing so, all fans run at 100%. so after i got a successful boot (it took many tries again even after resetting my bios), i would go into bios and reduce the fan speed a bit. i then saved and exited the bios. the PC just turned off and not start on its own until i pressed the power on button (i think).

this is my MB: ASRock > H77 Pro4-M

i find it really strange that IF the PC boots correctly, it will run for hours w/o any problems. but the next time i try to boot it, i will not get a display. as i said, eventually after turning it on and off multiple times it would then work again.

could this be a problem with my PSU? if this is most likely, is there any way to confirm this w/o buying a new one? i do not have a 2nd one available to try it.

what else could be the problem and how might i go about fixing it?

thanks a lot.

i filled in the stuff i know, i might have to look deeper into it, in case any specific information is needed. if so, which?

added the PSU to my system specs.
not sure about the exact graphics card model.
i checked dxdiag and it does not tell me anything else. i might have to open up the PC and see if i can find any more information on the card itself. might be hard since i had to install a new graphics card cooler about half a year ago or so. also kinda reluctant to shutting down the PC since getting it to boot back up takes so long ill see what i can do next time i boot.

also, thanks for ur quick replies.

lol, I had the same thing happen, it turns out the monitor cable to the back of the pc was not fully pushed in. It had come a little bit loose when I pulled the pc away from the wall to check something.

Caslon said:

lol, I had the same thing happen, it turns out the monitor cable to the back of the pc was not fully pushed in. It had come a little bit loose when I pulled the pc away from the wall to check something.

what i find strange though is that red LED on the fron panel of my PC that will not light up whenever i get "no signal" but once i DO get signal it will light up. pretty sure that led is connected to my harddrive.

also, if it was the monitor cable, why do i not get a signal 9/10 times when booting, but 1/10 it works fine and the pc will run for hours w/o problems. was this the case for you too? i would imagine if the cable wasnt plugged in correctly, that i would either get no signal ever, or the image would flicker or something.

oh, i just remembered: i already tried another monitor. didt work. unfortunately i do not think thats it.

ill do that again and report back.

did not find any loose cables inside my PC.
do you guys think that my before-mentioned problem could cause any problems when updating from win7 to win10?
as i said, everything runs fine, only problem is restarting/booting, which simply results in "no signal" 9/10 times. will this interfere with win10 update and cause trouble?