Question Asus P8Z77-WS: interpreting diagnostic lights

jhsachs

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Apr 10, 2009
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I've built several system over the years, but I've never encountered this problem. I wonder if anyone can tell me what to look for.

I'm building a system with an Asus P8Z77-WS motherboard, i7-3770 CPU, and two 4 GB RAM modules. The motherboard powers up, resets, and powers down, but the system won't start.

The motherboard has diagnostic lights that are supposed to tell me which component is at fault: the CPU, RAM, display, or disk light comes on and stays on, and that fingers the problem component.

But it doesn't work that way. When I power up, the CPU light comes on. It stays on for about 25 seconds, then it goes off, and the RAM light comes on for about one second. Then it's lights-out for a while (a minute or more past power-on, I haven't timed it), and the display adapter light comes on and stays on.

The hard disk light doesn't get into the act... perhaps because I haven't attached a disk yet.

In case it matters, the board was sitting in a box for several years with no battery installed. I put in a fresh battery before I started testing.

Any ideas?
 

rk8

Apr 9, 2022
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  1. Try to unplug the discrete graphics card (if you have one), then plug in the DVI port of the motherboard (you can use DVI to DP or HDMI, if you don't have a DVI monitor)
  2. Try to check whether the CPU is overheated. The drying of the silicone grease may cause the heat dissipation performance to be low, resulting in the self-test not being completed, and then the CPU will overheat and shut down.
  3. Disconnect the power, don't put the BIOS battery in it, then wait for 5 minutes to boot, if you can, try to long press the power button to let it discharge
  4. Change the memory stick
 

jhsachs

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rk8, thank you for your response. Here is current status:

1. Actually I tried the integrated graphics, and the system failed, before I added a discrete graphics card, and it still failed.

2, I don't know how to determine whether the CPU is overheated when the system won't come up at all. But you mentioned the grease drying -- I don't know how long that might take, but I installed the cooler (a brand new Noctua NH-U14S) less than a week ago. It seems unlikely that the thermal paste could have dried that fast. I suppose it's possible that I applied it incorrectly, although I followed the cooler instructions. Also, I've done this several times before and never had a problem.

3. I understand you mean that I should try to start the sytem without putting the battery back in. That seems unusual, but I tried it, and got the same failure.

4. There is no memory stick. I'm not trying to boot yet -- just get through POST.
 

egda23

Estimable
I've built several system over the years, but I've never encountered this problem. I wonder if anyone can tell me what to look for.

I'm building a system with an Asus P8Z77-WS motherboard, i7-3770 CPU, and two 4 GB RAM modules. The motherboard powers up, resets, and powers down, but the system won't start.

The motherboard has diagnostic lights that are supposed to tell me which component is at fault: the CPU, RAM, display, or disk light comes on and stays on, and that fingers the problem component.

But it doesn't work that way. When I power up, the CPU light comes on. It stays on for about 25 seconds, then it goes off, and the RAM light comes on for about one second. Then it's lights-out for a while (a minute or more past power-on, I haven't timed it), and the display adapter light comes on and stays on.

The hard disk light doesn't get into the act... perhaps because I haven't attached a disk yet.

In case it matters, the board was sitting in a box for several years with no battery installed. I put in a fresh battery before I started testing.

Any ideas?
What PSU are you using, and it's age ?
 

jhsachs

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I first tried a Tagan BZ1300, then a Tagan BZ900. I don't know how to tell the age; both were salvage. I have tested both in other systems, although not recently.

Later -- I substituted known good RAM and a known good video adapter. Still no go. I think that limits the possible causes to:
  • Defective motherboard
  • Defective CPU
  • Incorrect installation of something
Of these, I think the first is most likely. The board is also salvaged; most of the salvaged parts I try work fine, but there are always exceptions.

I think my next step must be to take the mobo/CPU/cooler assembly apart, reassemble it with a different motherboard, and see if that helps. That's my least favorite way of fixing a problem, but at this point is seems most likely to work.

Any further thoughts before I do that?
 
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