There is no signal coming to the monitor. wtf?

Question

Iron

The situation is as follows: when the computer is turned on, in 30% of cases the monitor starts showing the start screen, that is, it receives signals from the computer, and in 70% it does not. Sometimes it happens that at the start the image starts to be displayed, but disappears after a few tens of seconds. At the same time, I do not remember the case when the monitor turned off after it had worked for several minutes.
For the test, I connected the monitor to the laptop, and in 100% of cases the monitor turned on immediately. From this I concluded that he was all right.
Suspicions of a malfunction fell on the video card, which was already old, and I changed it. But to my surprise, the situation has not changed with the new map. Just in case, I also replaced the cable, but it did not help.
After the purchase, I realized that it was possible to plug the monitor into the output of the built-in graph. cards. I did so, but the monitor did not work again, since no signals were received.
Comrades, tell me, please, where is the problem?

Answer 1

Motherboard most likely.
Disable everything unnecessary (memory sticks, HDD, CD/DVD, etc.). Try to identify the buggy part. Did not work out? Then...
Reset the battery - you can't enter the BIOS, and there may be settings like "enable built-in video if there is no card" and "do not turn off built-in video if there is a card" - I met a PCI video card that did not want to work with these options - xs why.
Did not help? Install another video card (preferably with a different interface). Check that the video card is in the very first slot (the very first PCI, or PCI-E).
If it doesn't work, put another motherboard. This will definitely help, because. there is nothing more to screw up.

Answer 2

We pull out the video, reset the BIOS (battery), connect to the integrated video, go into the BIOS, set only PCI video (or whatever), save, turn off the computer until the BIOS loads, put the video, connect to it, PROFFIT.
If they didn’t go beyond the 3rd step - mother. I have never seen such glitches with the BP.

Answer 3

or PSU or motherboard manufacturer ESC. (Elite Group)

Answer 4

Perhaps something with the north bridge on the motherboard, as a variant of overheating.