Monitor will not turn on from cold boot.

[kenilik]

The Opening:
Although my system appears to boot normally, my monitor will not turn on from cold.

History:
The system has never worked correctly. I built my father a new mid-range gaming PC for his simulators about 4 weeks ago. I have reasonable experience building PCs. I've never had any problems with systems I've built in the past. I own and use a static band when tinkering.

The Full Story:
■If I reboot this system right now - no problem.
■If I power down or let the system sleep then restart or wake it immediately or within a few hours - no problem.
■If I power down or let the system sleep then restart or wake it after several hours - the monitor will not turn on.

This is not an intermittent problem. I can reproduce with certainty every time. I cannot work out exactly how long the system has to be off before the monitor won't turn on - at best it is between 4 and 7 hours before the problem occurs.

I do not believe there is a problem with the system boot sequence. There are no error beeps. The CPU, PSU, fans ,HDs, lights all make the right noises/flashes when the system boots even when the monitor does not turn on.

To get the monitor working - I have been waiting till the system has finished its boot sequence then doing a hard reset (holding down power button - using reset button does not work). Most times I only have to do this once however periodically I have to do 3 or 4 hard resets before the monitor turns on - VERY ANNOYING!

The Specs:
All hardware is new out of the box.
CPU: i5 3470 @ 3200Mhz
MB: Gigabyte Z77-D3H
RAM: G-Skill 2x4Gb DDR3-SDRAM 800Mhz
CPU cooler: stock Intel
Video Card: AMD Radeon HD 7850
Monitor: LG Flatron E2351
PSU: Seasonic 620W
HD: OCZ Vertex SATAII 120Gb SSD, Seagate Barracuda 1Tb HDD, DVD writer.
OS: 64b Win7 Home Premium
No other hardware.

I have tried:
1. Updating the latest GPU drivers & windows updates.
2. Different DVI/VGA/HDMI connectors to the monitor.
3. Alternating the DVI ports on the GPU/MB
4. After searching on Tom's Hardware yesterday: taking whole system apart and re-seating all components. Reconnecting all PSU plugs. following this excellent link carefully!.
edit
5. Tried different monitor on problem PC.
6. Tried disabling PLL Overvoltage in BIOS - as per a number of other suggestions around PC's not waking from sleep.
7. Switching monitor off and on (repeatedly) after boot has no effect. Get monitor no input message and monitor goes back to standby.

Any help would be appreciated. I can just imagine my discussion with the shop if I have to take components back and I turn it on in store and everything works wonderfully!!

Thanks,

S

 

[macusn]

How about switching the monitor with Dad's and see if it still does it?
Mac

 

[kenilik]

How about switching the monitor with Dad's and see if it still does it?
Mac

Thanks, should have had this at top of list of things already tried.

 

[macusn]

So when you wake it, you can hear the pc starting? What if you turn the monitor off and then back on again (after the wake) will it work then?
mac

 

[kenilik]

So when you wake it, you can hear the pc starting? What if you turn the monitor off and then back on again (after the wake) will it work then?
mac

Switching monitor on and off after boot has no effect. I just get a message saying that there is no input to the monitor and it goes into standby.

 

[macusn]

Just to verify, the monitor is indicating no input on the correct input method, no input DVI when you have it connected to the DVI port, or no input HDMI when yo have it connected to the HDMI port......ect.. What BIOS are you on? I don't see that we checked the power supply yet. Do you have another known working PSU that we can put in this PC and isolate this possible issue.
mac

 

[kenilik]

Confirmed, your summary of the display on monitor is correct. The monitor either shows 'no input' or does nothing at all. If I turn the monitor on and off after the PC has woken or booted then I get the 'no input' message and the monitor goes into standby.

I have the PSU in my own PC but its not as high spec'd as the new one I put together for Dad. Will have to check whether I can do a swap... I suspect not but I'll look into it and get back to you.

 

[Proximon]

Sounds as if your PSU fails when it's cold. Sends the power_ready signal too early or some such.

Any ATX PSU over 300W should work for a test.

 

[kenilik]

Not that I'm doubting the wisdom of other far more knowledgeable than I, but I'm curious as to how the PSU actually affects the monitor? They are connected via DVI in my case and obviously the monitor has its own power supply. I'd have imagined that the 'ok turn me on, here's some input' message from the GPU to the monitor would be of almost insignificant voltage that any PSU would handle.

In saying that, I've had a second suggestion to try and eliminate the GPU - an obvious one really. I'm going to try removing the GPU from the sys altogether and connect monitor DVI to MB (I've only tried this in the past without removing GPU).

I've got some new things to try so thanks. Will report back success or failures - just need my Dad to get back from holiday so I can try them!

 

[Proximon]

I do not believe there is a problem with the system boot sequence. There are no error beeps. The CPU, PSU, fans ,HDs, lights all make the right noises/flashes when the system boots even when the monitor does not turn on.

I did miss this on the first read through. However, your description leaves me wanting. I'm not convinced your system has really booted properly.

A PSU that functions right takes a very small amount of time to warm up... the power output stabilizes during this time, and then the PSU sends a signal to the PC saying it can safely boot up.

A defective PSU can take longer to warm up, yet sends it's ready signal early. This results in unstable power being fed to the system causing it to lock.

When your PSU is WARM, you get a good boot.
When your PSU is COLD, you fail to get a good boot.

I think it might be the PSU because it is the only part that can actually take hours to cool down. The CPU and GPU take much less time.

This unstable power MIGHT also cause your GPU to lock and result in a black screen or no signal. So, removing the GPU COULD apparently fix the problem when the problem is really the PSU.

What video card do you have exactly? There is no 7800, there is a 7850 or a 7870. You might try swapping the power cables to it.

 

[kenilik]

OK. Finally solved it!!! I tried a different PSU and had the exact same problem.

As I was gazing into the depths of the case wondering where too now... it occurred to me that there are TWO GPU slots. I swapped the GPU to the other slot and voila it works perfectly!