Mystery PC powers on and off, repeatedly

[mdopro1]

Hi folks, I'm in a bit off a jam and about to blow a gasket. I upgraded a computer for client and now I'm getting repeated on/off cycle and I need help. Following is the scenario.

Re-used items:
- Case
- Video Card
- Wifi PCI card
- Sata hard drive
- Power supply

New parts:
- Gigabyte motherboard
- i5 CPU (stock heatsink)
- 8GB DDR3 memory
- PCIe firewire card
- 3.5 bay USB 3.0/card reader/eSata

Assembled everything, computer started fine and loaded into existing windows install without BSOD but needed drivers, then out of nowhere lost power and restarted, then power on/off cycle began every 5 to 10 seconds on, then off and repeat.

I removed PSU, video card (motherboard has built-in GPU) and then tried again. Immediately after powering on I got on/off cycle.

I replaced memory, same result.

I replaced the CPU, same result.

So I figured it was the motherboard, I got a replacement motherboard and immediately it was the same effect on replacement part. This is where I started banging my head.

I got a new (third) motherboard and did not hook up anything other than a fresh PSU. I didn't even hook up CPU and memory. Motherboard was assembled in the case and third board did the same thing.

At this point there's only one thing, the case. So I get a new Cooler Master case. Put barebones together and it works fine, loaded into windows and half an hour later the system power cycles.

I figured some old part (case?) might have contaminated the board diodes and capacitors??? (if there's such a theory)......

Now I've gotten fourth board.

Battle plan for tomorrow:
Install board in new case, use third fresh power supply, nothing else installed - not even CPU and let the board stay on for a few hours. If it stays on, then install one thing at a time with few hours runtime in between each part.

So far I have discarded and refuse to install all old parts from old computer including wifi card. To my surprise the client is agreeing to all this, obviously his bill has gone up dramatically.

Some things to consider:
Gigabyte H77M-D3H motherboard
Topower 500 watt PSU
Crucial DDR3 1300 (i believe)
Cooler Master case
i5 CPU
1TB WD Black HDD
Old 320gb sata HDD (can't remember brand)

Is there anything that I'm doing wrong? Did I mix up parts to kill other parts that in-turn are killing the new board? Is that even possible?

Help please, for my sanity. I've already lost money on this computer and that's fine but I just want this thing out of my store because time spent on it is affecting other jobs.

Help!

EDIT: Something to note, 3.5 inch bay powered on but didn't work when I plugged in a USB stick to it. Maybe it's a bad reader killing everything? Possible, but there were times when it was not installed with same results.... so I don't know whether to ignore this fact or not.

 

[katz]

You've already done a lot of swapping/troubleshooting of parts. I would start with a linux/boot disc & see if it cycles off while running that. If it does, at least we can point to a hardware issue at that point.

 

[mdopro1]

I have an answer to that. All of these parts also did power cycle in BIOS, so no windows loaded. I suppose it doesn't hurt to try but have a feeling that it will have same result.

I also fresh loaded OS on a separate drive, even though I was able to keep machine on for installation process but shortly after it did crash as well.

Does anyone believe in ghost? Because that's all I can think of

 

[NYJimbo]

"Now I've gotten fourth board."

Can you explain to us what reasoning would cause you to do this ? Stop throwing everything at this machine, its not getting you anywhere. You must be overlooking something or mixing good and bad things together and losing track of what you did.

You might also want to consider your AC power, I know its a long shot but we dont know what you are plugging into and if it is being overloaded.

 

[katz]

If I understand correctly, it even power cycles when your in the bios?

I almost get the feeling that there is a shorted part. I know you've probably been down this road, but look closely at anything that the motherboard is touching that it shouldn't be.

A couple of years ago I got a mystery machine to work on. The guy assembled it himself, all new parts. It would freeze & random reboot. What I *finally* discovered was this:

When he installed the mobo, he misaligned that small rectangle insert in the back of the case where all the onboard stuff is (audio jacks,video,usb,etc) and a metal tab was ever so slightly bent & protruding into a usb port.

I had to look close to even notice it. I bent it away from the port & had no more issues. This was after I spent a couple of days looking over the os/ thought maybe there was a driver issue, etc.

Good Luck - I can't wait to hear what the fix is on this one.

 

[nlinecomputers]

Did you replace the POWER SUPPLY with a newer larger unit? I don't see where you have replaced that. With a power cycle issue that would have been the first item I would have replaced.

I would also confirm that you connected the front panel correctly. A pin off on your front panel connectors could give you reboots.

Edit: Ok I did see new PSU but did you go with a larger one?

 

[mdopro1]

"Now I've gotten fourth board."

Can you explain to us what reasoning would cause you to do this ?

Fourth board so I can connect it to everything fresh.

You might also want to consider your AC power, I know its a long shot but we dont know what you are plugging into and if it is being overloaded.

Everything else is working fine, this machine has been plugged to every almost every outlet since it's moved around in the shop so much. All AC outlets are known good.

If I understand correctly, it even power cycles when your in the bios?

I almost get the feeling that there is a shorted part. I know you've probably been down this road, but look closely at anything that the motherboard is touching that it shouldn't be.

That's why I got a new case. I could use nylon insulating washers between motherboard and raise screws in the case but that might cause problems with lack of ground.

When he installed the mobo, he misaligned that small rectangle insert in the back of the case where all the onboard stuff is (audio jacks,video,usb,etc) and a metal tab was ever so slightly bent & protruding into a usb port.

In this case I have also tested on wooden benchtop with nothing else other than CPU and memory, same effect.

Did you replace the POWER SUPPLY with a newer larger unit? I don't see where you have replaced that. With a power cycle issue that would have been the first item I would have replaced.

Two power supplies, it was the first thing I replaced since we were originally using old supply. First one was 430watt, new one was 500watt. I don't think I would need to go higher than that for single harddrive, bare motherboard with single CPU and two pieces of memory. But that could be an option if tomorrow brings disappointment.

I would also confirm that you connected the front panel correctly. A pin off on your front panel connectors could give you reboots.

When I was testing one of the boards (can't remember which piece) on the wooden bench, I skipped on all front connections and used tweezer to manually short power connector on motherboard, so there were no connectors other than power led connected to the board, obviously to see if it power cycles. But since then the case was replaced thinking it could be a shorting LED or even shorting power button.

I've got a few suggestions to try out for tomorrow, I wish me best of luck.

 

[drjones]

Did you try a brand-new power cord for the PC? I saw one of those go bad once.

 

[nlinecomputers]

At this point I'm with Jimbo. Your AC power is got a problem. Slap a good UPS on your bench.

 

[mdopro1]

Did you try a brand-new power cord for the PC? I saw one of those go bad once.

Used different cords throughout the troubleshooting process since everytime machine ended up on different bench.

At this point I'm with Jimbo. Your AC power is got a problem. Slap a good UPS on your bench.

Perhaps, even though other systems don't seem to have a problem with anything maybe a UPS will eliminate that part. Maybe power cycle the entire store to reset everything overnight or something.

A few things to try tomorrow morning. I'm actually scared of going to work for sake of my sanity. There was a point I almost wanted to throw this machine on the wall, but 600 bucks stopped me.

 

[Blue]

I'm a bit perplexed as to why you'd go through four motherboards, but at least you're persistent.

From what I've read, those boards' RAM slots seem to drop dead one after another, IFF they go bad. I'm not saying "there's your problem," but it's something of which to be aware. I would agree that running the board without anything in it might narrow things down, but you'll need a CPU in order to use the 'on-board' graphics. See if you can use different, known-good RAM, and test with the motherboard NOT in the case. Don't be afraid to break out the DVOM and check voltages, or better yet, use an oscilloscope to see whether the rails are clean -- I know that last item is a long shot with most shops, but many of us know people who own one.

 

[mdopro1]

I'm a bit perplexed as to why you'd go through four motherboards, but at least you're persistent.

From what I've read, those boards' RAM slots seem to drop dead one after another, IFF they go bad. I'm not saying "there's your problem," but it's something of which to be aware. I would agree that running the board without anything in it might narrow things down, but you'll need a CPU in order to use the 'on-board' graphics. See if you can use different, known-good RAM, and test with the motherboard NOT in the case. Don't be afraid to break out the DVOM and check voltages, or better yet, use an oscilloscope to see whether the rails are clean -- I know that last item is a long shot with most shops, but many of us know people who own one.

Check voltages from PSU or on the motherboard? I have a tester for PSU which either lights up or doesn't if power is not correct. It seems to work nicely in the past and this new PSU came clean. Don't know what happens under load though.

I will use testing "known good" stick of 2GB DDR3 tomorrow for a few hours.

 

[Blue]

Check voltages from PSU or on the motherboard?

Both, if possible. Many boards have test points/pads, usually a bare tinned area with the point labeled (though sometimes cryptically). It's a little risky, but not difficult. Just be sure your DVOM is set to measure voltage, not amperage! If you cannot find test pads, at least measure the PSU's rails, and make sure they're within (ATX) specifications.

Just a side note/FYI: I've never been a fan of test equipment that costs less than $100 or so. Most of the $20 ones I've taken apart use simple comparators and/or BJTs arranged to turn either a red or green LED on to indicate "failure" or "good", respectively. As fast as the switching speed is in a PSU's regulator circuits, and given the range of "good" voltages likely to be designed into the testers, I think a PSU could easily be malfunctioning and not be picked up by the tester. The noise on cheap PSUs is nothing to pass off as unimportant, and regulation usually gets worse with time and heat.

Check out the oscilloscope captures on this page for examples of some wonky regulation (click the pictures to make them larger): http://www.hardocp.com/article/2010...100m_1100w_power_supply_review/8#.US3IR1dkn3o

 

[nlinecomputers]

PSU testers are OK for obvious failures but it can't really report on all issues. I've had plenty of bad PSUs that pass on those testers. When you put it on a DVM you see spikes.

Don't have an oscilloscope but I'm sure it would show the issues even better.

As for UPSes. No system on my bench is unprotected. I'm not going to risk the liability of some wiring fault or a brownout or spike killing a client's PC. The power jumps all the time around here. Gotta have clean power.

 

[HFultzjr]

Hi folks, I'm in a bit off a jam and about to blow a gasket. I upgraded a computer for client and now I'm getting repeated on/off cycle and I need help. Following is the scenario.

Re-used items:
- Case
- Video Card
- Wifi PCI card
- Sata hard drive
- Power supply

New parts:
- Gigabyte motherboard
- i5 CPU (stock heatsink)
- 8GB DDR3 memory
- PCIe firewire card
- 3.5 bay USB 3.0/card reader/eSata

Assembled everything, computer started fine and loaded into existing windows install without BSOD but needed drivers, then out of nowhere lost power and restarted, then power on/off cycle began every 5 to 10 seconds on, then off and repeat.

I removed PSU, video card (motherboard has built-in GPU) and then tried again. Immediately after powering on I got on/off cycle.

I replaced memory, same result.

I replaced the CPU, same result.

So I figured it was the motherboard, I got a replacement motherboard and immediately it was the same effect on replacement part. This is where I started banging my head.

I got a new (third) motherboard and did not hook up anything other than a fresh PSU. I didn't even hook up CPU and memory. Motherboard was assembled in the case and third board did the same thing.

At this point there's only one thing, the case. So I get a new Cooler Master case. Put barebones together and it works fine, loaded into windows and half an hour later the system power cycles.

I figured some old part (case?) might have contaminated the board diodes and capacitors??? (if there's such a theory)......

Now I've gotten fourth board.

Battle plan for tomorrow:
Install board in new case, use third fresh power supply, nothing else installed - not even CPU and let the board stay on for a few hours. If it stays on, then install one thing at a time with few hours runtime in between each part.

So far I have discarded and refuse to install all old parts from old computer including wifi card. To my surprise the client is agreeing to all this, obviously his bill has gone up dramatically.

Some things to consider:
Gigabyte H77M-D3H motherboard
Topower 500 watt PSU
Crucial DDR3 1300 (i believe)
Cooler Master case
i5 CPU
1TB WD Black HDD
Old 320gb sata HDD (can't remember brand)

Is there anything that I'm doing wrong? Did I mix up parts to kill other parts that in-turn are killing the new board? Is that even possible?

Help please, for my sanity. I've already lost money on this computer and that's fine but I just want this thing out of my store because time spent on it is affecting other jobs.

Help!

EDIT: Something to note, 3.5 inch bay powered on but didn't work when I plugged in a USB stick to it. Maybe it's a bad reader killing everything? Possible, but there were times when it was not installed with same results.... so I don't know whether to ignore this fact or not.

Sounds like some kind of a power issue.

Just a shot in the dark...ARE YOU SURE all components are correctly compatible with your configuration. Motherboard, Ram, CPU, etc, and is your wattage of the power supply ample?

 

[mdopro1]

Both, if possible. Many boards have test points/pads, usually a bare tinned area with the point labeled (though sometimes cryptically). It's a little risky, but not difficult. Just be sure your DVOM is set to measure voltage, not amperage! If you cannot find test pads, at least measure the PSU's rails, and make sure they're within (ATX) specifications.

Previous motherboard won't power on, so no point testing where the problem is because it is getting RMA'd. I tested (second) PSU with DVM and it's clean. However, I still put on a new PSU this morning.

Check out the oscilloscope captures on this page for examples of some wonky regulation (click the pictures to make them larger): http://www.hardocp.com/article/2010...100m_1100w_power_supply_review/8#.US3IR1dkn3o

Will do, thanks.

PSU testers are OK for obvious failures but it can't really report on all issues. I've had plenty of bad PSUs that pass on those testers. When you put it on a DVM you see spikes.

You're right, I've had PSU's pass the tester but won't power on the computer before... in the past with other computers.

Sounds like some kind of a power issue.

Just a shot in the dark...ARE YOU SURE all components are correctly compatible with your configuration. Motherboard, Ram, CPU, etc, and is your wattage of the power supply ample?

It's all pretty standard but yes it's compatible.

Update: Third PSU, Fourth MB, same CPU and memory running on the bench for over 1 hour with no power loss.

If I were to blame anything, it would be that 3.5in bay because it actually didn't work when I plugged in a USB stick. It has got to be that one part F-ing up everything. So far 1hour and we're good. I'll start adding hard drive, wifi, firewire card soon and one at a time.


UPDATE 2: So I hit CTRL+ALT+DEL while machine is in BIOS, system restars and is now power cycling again on/off -----urgh. CPU & Memory is the only two things in there.

 

[MobileTechie]

I cannot see how a new PSU (of sufficient rating) on a new motherboard, with new parts can possible have the same problem as the old parts. That is a different computer entirely at this point...other than the CPU

 

[NYJimbo]

Everything else is working fine, this machine has been plugged to every almost every outlet since it's moved around in the shop so much. All AC outlets are known good.

I just had to revisit this because nothing else seems to be working for you.
Are you SURE that you are not just using different outlets on the same AC circuit ? I know its a longshot but can you be sure you test it on a different breaker or circuit from your electrical panel ?

 

[brandonkick]

Given the fact that with the third PSU and fourth MB he was able to have it going for over an hour with no problems I would have to say that his power source is not the issue.


I suspect maybe the processor is to blame. I mean at this point you have very very little components to test.

Id say you either have:

1) A bad motherboard (for the forth time)
2) A bad i5
3) Ram that is either bad or incompatible with the motherboard.

 

[NYJimbo]

...I suspect maybe the processor is to blame. I mean at this point you have very very little components to test.....

Yeah but early on he says "I replaced the CPU, same result."