Question Previously working desktop requires multiple resets to eliminate black screen and allow log on.

Mar 22, 2019
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A previously very reliable desktop running Windows 10 will not allow the password screen to load on initial power up.
The computer remains running with all fans operational. The video screen attempts to load for a second and then goes black with monitor power led still lit.

If I hit the computer reset button the computer will reset then power back up, the monitor and keyboard LEDs will light and a screen will flash...then go black.
If I reset the computer multiple times over a 5-7 min period the password screen will finally load properly and the computer will function normally until I power down.

If after powering down....I immediately attempt to power the computer back up... sometimes the computer will restart normally...but most often the process of requiring multiple power resets over 5-7 mins will be required.

The computer has never failed to start and operate properly after spending up to 7 mins going through multiple resets.

Any Ideas where to look first?
Thank you.
 
Mar 22, 2019
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Intel i5-2500K CPU @3.30GHZ
Installed ram 16gb
64bit x64
Dell 2405 FPW
Windows 10 Pro
Primary 256 SSD
Data drive 1TB

I assembled this computer about 7-8 years ago and cannot recall the motherboard, video card or PSU used as I had several to choose from and have not opened this case since it was built.
Unfortunately, I am recuperating from eye surgery that was done yesterday and will be unable to pull the cover to investigate further for several days.
At that time I could switch out the PSU.
 

Centurion1479

Prominent
Jul 13, 2017
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If the monitor LED is flashing on and off, it could be your video card because the flashing indicates no video is being sent. If its just solid, im thinking a software problem because if the PSU or mobo was failing you probably wouldnt be able to even have it turned on for even 5 minutes if at all.
 
Reactions: owenslee
Mar 22, 2019
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The computer has failed to start today after repeated attempts. I have had to log on using my wife's desktop.
The monitor LED is a solid green after powering up with no flashing. present.
The computer appears to be running normally.
Cooling fans are running
Power lights are working.
I changed out the keyboard with no effect.

My vision is a little better today so I may open up the case and see which MB and PSU were used at original assembly.
 
Mar 22, 2019
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Ok...I removed the cover and additional details are:

MB: ASUS Sabertooth Z77

Video: GTX560Ti EVGA

PSU: NZXT 850W # HALE82-850-M

Three case fans

CoolerMaster CPU Heat Sink with fan

Plextor 256 SSD

Data Drive: WD1003FBYX SATA 1TB
 
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Mar 22, 2019
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If its just solid, im thinking a software problem because if the PSU or mobo was failing you probably wouldn't be able to even have it turned on for even 5 minutes if at all.
When the computer would fail to load the password screen but would finally start after 6-7 mins of resets...it suggested that the problem was worse when the computer was cold....and it improved the longer the computer was running.
Once running for several minutes... it would continue to operate normally all day without any issues, as long as I did not power down.
At that point the MB and PSU were operating without any issues.

At first I thought it might be going into sleep mode prematurely...but if so...it would never come out of sleep mode.
All I could do was hit the reset.

If no further suggestions are received...I may first try a second monitor. If no better...then I'll replace the PSU.
If it is a software issue...I don't even know where to start since I now can't sign on to do a reinstall of Windows.

All input is appreciated.

Thanks to Centurion 1479 and rgd1101...!

One added note...
This computer has been running unopened for 7-8 years immediately adjacent to an interior heating/AC supply duct.
Once the case was opened, it had a metric ton of dust accumulated inside the case. So much so that a vacuum was not able to get all of the nooks and crannies. I took the computer outside after removing both front and back access covers and used compressed air to clean the interior, boards and all components being careful not to spin the cooling fan blades excessively.
During computer operation and with the three large case fans there were no obvious signs of any overheating. All cooling fans continued to operate. Yet the accumulated dust clearly was reducing airflow into the case.
I am wondering if this reduced airflow was creating the problem.
Since household dust is (normally) not electrically conductive...I would be surprised if the accumulated dust effected a reduction in voltage of any exposed circuits.
???
 
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Mar 22, 2019
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Is it possible that my problem may be the result of a dying CMOS battery on the MB...?

I have not noted any loss of time settings previously when the computer was running normally...however the battery has never been replaced since the original build and it is now 7-8 years old.

The issue with the Z77 board is the lousy armor placed over the board that has to be removed to access and replace the battery.
 
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Mar 22, 2019
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Well...I have the computer up and running.
I have started it multiple times and Windows loads without issue.

All that was done was a complete internal cleaning of all the accumulated dust in the computer case.

The CMOS battery measured 3.16V... but was changed as it was 7 years old. New replacement battery measured 3.36V

The monitor tested fine on the bench.

The original PSU is working as intended.

The keyboard was replaced... but was working fine except that the keys were almost unreadable.

It bothers me that I was unable to definitively isolate the cause of the problem...however I suspect it may have been a bad, too short monitor cable that was slightly stretched and badly kinked at the back of the computer. I replaced it with a new cable. But I reattached the old cable while on the bench and... it worked fine. I may further check the continuity of each wire...but at this point the erratic video may have been a damaged failing wire that worked only occasionally.

The important point is that the computer is again...operational.
 
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