No graphics, computer don't start

Usernameis

Honorable
Nov 22, 2013
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10,530
Hi.
I got one desktop PC to fix (Gigabyte motherboard, 4GB RAM, external Graphic Card. I can't recall other specs. It is roughly 3 years old machine).

1. When I turn on PC, the monitor doesn't respond (gets no signal). Monitor is tested and definitely works.
2. All fans are spinning, all LEDs at PC box are lightning, but after running ~1min., it stops for ~5s., runs again for ~1min., stops for ~5s. and all the time like this.

My efforts:
- Unplugged power cable of DVD ROM
- Unplugged one of HDDs
- Pulled external graphic card off
- Unplugged second HDD
- Pulled out RAM memories one by one

After each step PC behaves exactly the same. The only thing I didn't try - other power supply (current one is 400W). I hope it is not faulty Motherboard (without RAM it keeps beeping a healthy sound).

May anyone else has any ideas or encountered similar issue? Thank you very much.
 

JOHNN93

Honorable
test the psu if it gives you the votages might be defect psu.
you can test it with a psu tester or with a multimeter.
to test the psu with a multimeter simply jump the green with a black wire on the 24 pin motherboard conector with nothing else conected.after have the black probe to a black wire and with the red start puting it on all the other wires one by one.your results should be.
orange 3.3v red 5v yellow 12 v blue -12 v.
rou might want to reset the bios by jumping the cmos reset pins or just by taking out the battery for 10 seconds when not in a power outlet.if its not a motherboard problem in should power up properly.test with only motherboard and ram first after start adding.
 

Usernameis

Honorable
Nov 22, 2013
36
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10,530



Thank you for advice. I will have a look this evening.
 

Usernameis

Honorable
Nov 22, 2013
36
0
10,530
I have tried other power block, didn't help.
Additional things I have done and solved this issue (Just not sure for how long)

1. Discharged RAM memory cards (slightly scraped contacts with rubber)
2. Took BIOS battery out for a several minutes.

What is it. It seems working. I will let you know if will fail again.