PC keeps powering...then shutting down...then powering...etc

Vanilla

Vanilla

Vanilla

Soldato
Joined
18 Oct 2002
Posts
9,522
I have had this PC for about 6 months. Initially all was OK but then one day a few months back it would start up, then shut down, etc. I removed the battery, cleared the CMOS and it worked.

Now I have moved the PC to a different house and it is doing it again (1 mile car journey, very short).

Spec

Intel i7, VTX3D 7850HD, Corsair AX650 PSU, 16GB Samsung Green (4GB x 4), Gigabyte Z77X-D3H Intel Z77.

Symptom:

- Upon powering PC fans will start up and then the PC will shut itself down within 7 seconds. It then turns itself on and shuts itself down again.
- Nothing comes on the monitor, PC does not post.

What has been tried

- Battery removed overnight, CMOS cleared. Unsuccessful.
- Removed from case and built PC on desk. Removed all RAM apart from 1 stick, removed graphics card. Just CPU, one stick of RAM and PSU. Unsuccessful.

Any ideas what to try next before I order new stuff :p
 
I'd be willing to bet it's your PSU. Do you have a multi-meter or can you borrow one to test it? (they're only a few quid online if not, and worth having anyway).

I had the same symptoms and my PSU, although outputting correct voltages on all the rails, wasn't sending the Self-test OK signal to my cpu to boot.
 
Vanilla said:
I have had this PC for about 6 months. Initially all was OK but then one day a few months back it would start up, then shut down, etc. I removed the battery, cleared the CMOS and it worked.

Now I have moved the PC to a different house and it is doing it again (1 mile car journey, very short).

Spec

Intel i7, VTX3D 7850HD, Corsair AX650 PSU, 16GB Samsung Green (4GB x 4), Gigabyte Z77X-D3H Intel Z77.

Symptom:

- Upon powering PC fans will start up and then the PC will shut itself down within 7 seconds. It then turns itself on and shuts itself down again.
- Nothing comes on the monitor, PC does not post.

What has been tried

- Battery removed overnight, CMOS cleared. Unsuccessful.
- Removed from case and built PC on desk. Removed all RAM apart from 1 stick, removed graphics card. Just CPU, one stick of RAM and PSU. Unsuccessful.

Any ideas what to try next before I order new stuff :p
Click to expand...

Search for gigabayte loop of death, there is another way when you power on PC and then rip out the cable its the 3rd and last option with infinite death loop.. Give it a go, might do something.
 
Vanilla said:
My neighbor is an electrician so I can get one i'm pretty sure.

What do I need to do once I get one?
Click to expand...

It's pretty straightforwards.

This is a decent guide here

Pay careful attention to the PWR_OK/Power Good (the grey wire, PG in their diagram), because even if the other voltages are perfect, if the PSU doesn't give the okay to boot it won't and you'll get that loop of constant POSTing.
 
Multimeter test results:

1 = 3.3v
2 = 3.3v
3 = 0.1v
4 = 5.3v
5 = 0.0v
6 = 5.3v
7 = 0.0v
8 = 5.3
9 = 5.10
10 = 12.1
11 = 12.1
12 = 3.36

13 = 3.36
14 = -12
15 = 0
16 = 0
17 = 0
18 = 0
19 = 0
20 = 0
21 = 5.3
22 = 5.3
23 = 5/3
24 = 0

I think this means the PSU is ok, everything looks normal.
 
Use the basic parts needed.

Remove all drives.

Anything apart from keyboard+mouse in the USB ports?
 
The multi meter tells you something but not a lot as you are not putting any load on the PSU.

Do as stulid says above.

If it dosen't work i would bet its the motherboard. Do you have another PSU you could use to test?
 
jamesfreddie said:
The multi meter tells you something but not a lot as you are not putting any load on the PSU.

Do as stulid says above.

If it dosen't work i would bet its the motherboard. Do you have another PSU you could use to test?
Click to expand...

I had a few disk drives plugged into the PSU when i did the multimeter test.

When I as just testing the multimeter the PSU behaved well, it stayed on constantly and did not try to reboot itself.

The PSU fan did not come on but then gain this is expected, it only comes on under real load.
 
OK, took off the HSF, had a look at the CPU. Could see nothing out of the ordinary. CPU seems fine, mobo socket pins seem fine.

I reseated the CPU and put the HSF on top. Same thing.

Tempted just to wander down to the shops to pick up a mobo......100 quid bet but I'm strongly leaning towards the mobo being the issue
 
what bios version were you running on the gigabyte?theres been a big improvement with samsung green support on gigabyte boards lately so it could have been that
 
Glad you got it sorted mate. With these it's almost always the PSU or mobo. I RMA'd my mobo and it turned out to be my psu (costly mistake on my part), but at least you narrowed it down in the end. How long did you have your board before it started playing up?
 
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