random POST failures - expert advice needed.

[ow69]

Configuration:
MB: GA-Z77-DS3H
Video: Nvidia GeForce 650GTX TI 2GB-5 EVGA
RAM: Corsair 8GB DDR3 1600MHZ

I am trying to identify a problem that plagues my computer for several months, your assistance is much appreciated.

The main difficulty is that the symptoms are inconssistant. That is, they may appear for awhile, then, for a time, everything works fine.

The system still under vendor warranty, so I took it to the vendor's lab twice already. Once they replaced my video card, once the RAM. Both times the system seemed to be working fine for a few weeks, then the problems re-appeared with increasing frequency.

I experience 3 symptoms, which I believe all relate to the same core problem:

1. Random horizontal lines flash on the display - see http://www.youtube.com/watch?v=rsZmcSgqXQ4

2. Random occasional blanking of the screen - see http://www.youtube.com/watch?v=D09kVRrLqxg

3. POST failure on boot. Power is up, fans are spinning, HDD lights blink, but no OK beep, no BIOS screen.

Even the POST failure comes and goes with no apparent reason.


Last time I had the POST issue, I tried  some troubleshooting:

1. removed RAM - got multiple beeps at boot, indicating no RAM, which is expected.

2. remoed video card - got a series of long and short beeps, which is also expected.

- When I put the parts back, beeping stopped.

3. disconnected HDDs, DVD - no effect.

System seemed completely dead.

After a few hours, the system booted back normally.

I am suspecting some malfunction of the MB, but found no way to prove this.

Any experts out there can share some insights?

thanks,
Omer

[dmdilks]

Have you tried it with the on board video?

[ow69]

Thanks, and sorry for the late reply. Didn't get around to testing.

Last night I tried plugging the screen to the integrated graphics.
System didn't switch to use it when I set the BIOS to auto. Guess I need to remove the eVGA card to test it properly. Will update.

[hal8000]

I had problems with random shuttingdown and random turning on, turms out was the case
on/off button.

This may mot be your problem but turn off the power, unplug from electric socket. If you can get access to front
case on/off switch blow compressed air over it to remove dust/debris.
Then operate on/off switch about 50 times fast to clean contacts.

Switches being mechanical in nature often cause intermittent and unexpected problems.

Post back if it solves your problem.