PC cycling on and off and won't start

csebasti

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Apr 27, 2012
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I could use some help troubleshooting my PC boot issue. When I press the power button, the lights come on, all the fans spin up, the hard drive spins up. Nothing on the monitors, and after 20 seconds it shuts off, then restarts. It continues to do this, and currently every other cycle, one monitor comes on with the usual BIOS screen, then goes to black with a cursor in the top left corner, then to a screen I've never seen before just saying "GIGABYTE - UEFI DualBIOS" at the top. Then it shuts off and starts the cycle again.

HISTORY:
I built the computer (specs below) just over 5 years ago now and have never had a problem with it. It is my first build. About a week ago, I shut the computer off while getting ready to head out on vacation. I had two USB devices plugged in and tried to eject and safely remove them, but the first one hung up and didn't seem to be working. I then just shut the computer off, and realized I forgot to get some files off it. I tried turning it on and it started the cycling mentioned above except that the screen only came on every 3rd cycle. I don;t understand what would cause the very consistent cycling with the monitor coming on every 3rd cycle or every 2nd cycle. Maybe that is a clue to the issue.

SPECS:
Motherboard: Gigabyte GA-Z77X-D3H
CPU: Core i7-3770K
RAM: G.SKILL Ares Series 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 1600
CPU Cooler: COOLER MASTER Hyper 212 Plus
Video Card: VGA 02G-P4-2643-RX GeForce GT 640 2GB 128-Bit DDR3 PCI Express 3.0 x16 HDCP
PSU: PC Power and Cooling Silencer MK III 500W Modular 80PLUS Bronze
SSD: Samsung 850 EVO - 250GB
HDD: Western Digital Caviar Black WD5002AALX 500GB 7200 RPM 32MB Cache SATA 6.0Gb/s
OS: Windows 10
Case: Antec Three Hundred Black Steel ATX Mid Tower Computer Case


After returning from vacation, the computer did the same thing. I read the computer won't start troubleshooting thread on this forum and have done just about all the steps. At one point, it was cycling on/off about every 1 second. Here is what I've tried.

1. Removed main SSD drive, put into an enclosure and plugged into a laptop to verify it wasn't dead. No problem there.
2. Reinstalled the SSD and tried starting again. At this point the computer would only power on for about 1 second before turning off and repeating.
3. Manually tested the PSU with a multimeter with no load on the PSU. Everything was very close to nominal voltage. I expected to find something off here, but no luck.
4. Hooked up the power plugs again, but left non-essential items unplugged (DVD, Memory card reader, HDD dock). Tried testing PSU and testing again, but it was difficult with it only staying powered for 1 second at a time, and I was having a hard time fitting my multimeter leads into the back of the 24 pin connector. I did manage to take a few readings which were normal, but gave up after a while.
5. Reseated all connectors. No change.
6. Tried turning on again and got the same on/off cycle every 1 second or so.
7. Tried reseating the memory, single stick, swapping single stick, both sticks again. Tried starting with each combination and got the same results.
8. Reset the BIOS (screwdriver on jumper pins method). Pushed the power button and the lights and fans came on and stayed on. I didn't have monitors plugged in. I was pleasantly surprised that it stayed on. I plugged in the monitors, but had no video.
9. Turned off. This time to turn it off, instead of needing to hold the power button in for a few seconds, it shut off immediately when I pushed the button.
10. Turned on again, and it went back to the 20 second on, then off cycle with the monitor coming on every 2nd cycle. The keyboard doesn't appear to be recognized yet as the lights on it are not on, and pressing F12 to go to BIOS setup doesn't do anything. But after that screen switches to the black screen with cursor, the keyboard lights come on.
11. Tried removing the CMOS battery. Had it out for an hour or two, put it back in and got the same cycling.
12. Tried multiple additional CMOS resets and nothing changes.
13. removed video card and plugged monitor into onboard video. No change.
14. Checked power switch by doing continuity check. Checked out fine. Also disconnected teh reset button and still get same results.


What should I do next? I have no speaker, so I don't hear beeps. Should I buy a speaker and a POST test card? Does this cycling with the monitor coming on every 2nd or 3rd cycle mean anything?

Chris
 
Solution
Try to flip the connectors if you haven't already, instead of just reseating them. The positive pin is where the little arrow is if it doesn't say in text. I had the exact same problem as you until I flipped it because the negative side was on the +ve side. I know you'll say you didn't touch them before this problem occurred, because that's exactly how it happened to me. I guess flipping them just managed to fix it.
One of my friends also had this problem and found that re-plugging his fan headers in managed to do the job. You'd be surprised how weird these solutions get and I guess it varies per computer spec. Try thinking outside the box rather than testing the PSU or other components. In the end it will be the smallest thing and you'll feel stupid that you didn't try it before.

Best of luck! 😀
 


Something de-stablised or failed.

Just for the record, you have a PC Power and Cooling Silencer MK III 500W Modular 80 PLUS Bronze PSU. I'm assuming its about as old as your PC build. So, if it is 5 years old... it is probably near or at warranty too. PCP&C has traditionally been a good brand overall though, but it won't hurt to try a different PSU.

The stabilization issue could be a fan that isn't working, or seen as, for CPU cooling.

My experience hasn't been that easy as a fan failed should plain shut down the system, no reset/reboot. It has been CPU/RAM/Motherboard instability. If power was flaky (you can't exactly see it under no-load conditions, and an o-scope may be needed even then) it might do that too.

If any of these suggestions (mine, or others) don't work.. it could be CPU or motherboard issues.
 


Which connectors are you referring to to switch around? I'm pretty sure everything in there is clocked a certain way and can't be turned around. Are you talking about a two pin fan plug? That's about the only thing I can think of that could be turned around.
 


Yes, the PSU is original to the build. It is now about 5 years and 1 month, so just outside of the 5 year warranty. Unfortunately I don't have access to another PSU to try without buying a new one which I'd rather not do if I don;t know for sure that will solve the problem.

So speaking of a fan not working or seen as not working... I just watched all the fans again. On the cycles where the monitor does not turn on, the CPU cooler fan initially comes on, but then stops within about 5-8 seconds or so. It then twitches a little every few seconds like it's trying to run again. On the cycles where the monitor does turn on, the CPU cooler fan comes on and stays on the whole time. Seems strange to me.

I suspect it is likely the motherboard or the CPU, but I'd like to have a way to verify before buying a replacement.

The whole thing with the cycle of the monitor turning on every third cycle seems strange to me and seems like it would be a clue to the issue. But I'm new to this.
 
Ok, I bought a POST test card with a speaker, so now I have a little more info, but I'm not sure what the codes are telling me. With the card plugged into a PCI slot, I get two different results with #2 below happening about every 2nd or 3rd cycle and the computer continuously tries to turn on, then shuts off 20 seconds later, then turns on again, etc.

As the computer is cycling on and off trying to boot, one of two things happens:

1. All fans come on. I see a couple codes on the POST card, and it stops on 32. The CPU cooler fan turns off, and then twitches a little but never spins back up. I see nothing on the monitors. No beeps.

Or, this happens:

2. Lots of codes go by quickly. The CPU cooler fan stays on. I get a single short beep (if it matters, code 64 is showing when it beeps). It eventually stops changing codes and displays d6 until shutting off. I do get the BIOS screen on one monitor, but pressing delete or F12 as indicated on that screen to enter BIOS does nothing.

In all cases, the LEDs on the POST card indicating +12, -12, +3.3 v all light up as does the CLK LED. There is an LED that says "Frame". This never lights up.

I can't figure out what set of codes I'm supposed to be looking at for my Gigabyte GA-Z77X-D3H motherboard. I can't find Gigabyte codes. Am I supposed to be looking at something different? I think I saw something that pointed to "Award", but the list of Award codes does not include d6.

Can anyone help me out?

Chris
 
Well, I got it working yesterday. Turns out the error code for #2 above was db, not d6, and I found another thread saying that was a BIOS problem. Also found something saying that the keyboard needs to be plugged into a USB 2.0, not USB 3.0 plug in order to work outside of Windows. After swapping hte keyboard to a 2.0 plug, I was finally able to get to a screen saying they BIOS was being updated, and then would reboot. After that it went back to the same on/off cycling. after a good 40-50 attempts to get back into the BIOS I finally got to a screen saying the Main BIOS was corrupt and the backup would be restored. After that happened, it went back into the same on/off cycling. Another 40-50 attempts at getting back into the BIOS, and I finally got back in and flashed it with version F16 to replace F5. Restarted, and all is better now. So, it looks like I'm back in action.
 


That would do it. Sometimes the UEFI BIOS is what isn't stable for some reason and the newest BIOS usually helps. Me, it took about two BIOS updates to get things running 100% on one board I own.
 
Solution