Monitor Alternates Between Signal and no Signal

Starbucksguy · Aug 9, 2014

So, to get right into it: I have a custom built pc, originally from CyberPower but since modified. A couple months ago, the whole thing stopped working, and since I was going away for a while, I opted to let a computer repair store fix it for me. They installed a new motherboard, when I got home I installed a new CPU.

Now, I'm fairly certain everything is wired correctly, but when I attempt to turn on the pc, the monitor turns on, the indicator light turns blue to indicate that a signal is received, all the fans start up, and no warning lights turn on. After a second or two, however, the monitor goes into standby mode, and says "No Signal Detected." After another few seconds, the monitor indicator light turns blue again, it looks like the screen begins to turn on, and then it reenters standby mode and once again says "No Signal Detected." This cycle continues indefinitely.

I've tried DVI and VGA, using both the GPU output and the motherboard output, with the GPU installed and uninstalled. The cables work to connect my laptop to the monitor. Whenever I try to search for similar problems, all the results are for pcs where everything starts up but the monitor consistently shows no display, so I haven't found anything helpful. Right now I'm leaving the motherboard battery out to try to reset CMOS, no idea if that will help.

Thanks for any help.

CompGee · Aug 9, 2014

Put the motherboard battery back in in a minute or 2, and then post back! Good lick!

I MEANT LUCK!!!!!!!!!!

Starbucksguy · Aug 9, 2014

CompGee :

Motherboard battery is back in, but there is no change to the problem. The monitor still alternates between signal and no signal. Anything else I could try?

CompGee · Aug 9, 2014

Do you have any more good motherboards that you could use in the system with their rear I/O shields?

Starbucksguy · Aug 9, 2014

CompGee :

I have no alternate motherboards at all, unfortunately. I was assured that this motherboard was tested with a functioning setup by the person who repaired my computer originally, and the lights on the motherboard seem to indicate that it has no problem. If a parts list would help, I can supply it.

CompGee · Aug 9, 2014

Thanks! Would you please supply it to me?

Starbucksguy · Aug 9, 2014

A parts list as requested:
Asus P8Z77-V LK motherboard
Intel Core i7-3770 2.5 GHz
Nvidia EVGA Overlclokced GTX 670 4GB
2 4GB DDR3/ 1600 MHz RAM
1TB SATA III 7200RPM 3.5" Hard Drive
Asetek 510LC 120mm Watercooler
Xtremegear 600 Watt 80 Plus PSU

That should be the most important stuff. There's also four fans, maybe a few other small things, but I've currently stripped it down to the bare essentials.The motherboard, CPU, watercooler (which counts as the CPU fan), one stick of RAM, and the PSU. I have also tried reseating the GPU, attaching the other fans, and attaching the Hard Drive, but all setups result in the same thing.

As another note, this is the first time I'm troubleshooting a computer where I really don't know whats wrong. I've looked at a lot of online guides (including the thread here about no POST/no video), but I'm still in the dark. So, if there are any simple things that I might have missed, feel free to point them out.

CompGee · Aug 9, 2014

Have you tried the MB output after resetting the computer's CMOS?

Starbucksguy · Aug 9, 2014

After CMOS reset, I removed the GPU and plugged the monitor into the motherboard ouput, both VGA and DVI. the result is the same: the monitor turns on for a second, acts as though it is about to display something, and the goes into standby with the "No Signal" message. This repeats.

Edit: With the GPU installed and the monitor connected to the motherboard output, the monitor fails to react whatsoever. I believe the motherboard shuts off its graphics when a GPU is detected, but in case this is abnormal, I thought I should mention it.

CompGee · Aug 9, 2014

Have you tried the same cables and monitor on a different computer?

Starbucksguy · Aug 9, 2014

The VGA cable is able to connect my laptop to the monitor without fail. I don't have a computer with DVI ouput other than the one in question, so I can not determine if it works.

CompGee · Aug 9, 2014

Do you have a CLR_CMOS jumper?

Starbucksguy · Aug 9, 2014

CompGee :

From what I can tell, I do not. I have a CLRTC, or Clear RTC RAM jumper, but that's the only jumper I can see in the manual or on the board.

CompGee · Aug 9, 2014

Does the motherboard manual have instructions to clear the CMOS/RTC from those jumpers?

Starbucksguy · Aug 9, 2014

Yes, the manual has instructions to clear the CMOS using this jumper. I have already tried to clear the CMOS using this jumper, following the instructions; it did not help.

CompGee · Aug 9, 2014

Do you have another desktop system?

Starbucksguy · Aug 9, 2014

I have an old desktop that I haven't used in a while, but that's it.

CompGee · Aug 9, 2014

Try the monitor on that computer. If the same problem happens again, then the monitor needs to be replaced. If the issue doesn't happen, then the motherboard needs to be replaced in the computer in question.

Starbucksguy · Aug 9, 2014

The monitor works fine, I guess it's a motherboard problem. I'll look into it and see what I can do.

Monitor Alternates Between Signal and no Signal

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