the_deku_nutt

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Apr 21, 2012
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Hi all,


I have a custom built computer that has served me excellently for 7 months, until about 2 weeks ago I installed a new case fan. Upon attempting to boot up with the new fan, I received absolutely no response from the system. I removed the fan, and still received no response. The components of my build are as follows:

MSI 870-G46 motherboard

AMD Phenom II quad core processor

Sapphire 6870

8 GB of DD3 Ram

650W Rosewill Power supply


Upon initial failure, I thought the fault to be with the power supply due to the utter lack of response from any systems; however, the ethernet port indicator WAS active. It was still under warranty, so I sent in and received back a new power supply. I still receive no response. No fans spin, no lights come on, absolutely nothing other than the ethernet light.


My next step was removing the motherboard from the case and placing it on some newspaper on my desk to perform a simple post. I removed everything except the processor, ram, and power supply. I still received no response. Is there a way I can determine which component is faulty?


Thanks in advance to for any assistance.
 
sounds like the fan might have been bad or you shorted something out. did you have the power turned off at the power supply and the power pulled from the mb. most new mb dont completely power off when you shut them down. first rule i teach new techs if it a laptop/pc/monitor is pull the power from the wall and wait 5 before working on a unit. if the mb thinks you had a dead short sometimes you have to clear the cmos to wake those mb up. if you take your ram and video cards out of the mb on a table and it has a speaker...you should get some cmos beep codes if the mb is posting.
 
To echo smorizio's question, did you unplug the power from the wall before you did anything?

Did you touch the case before you touched anything else?

If you have the RAM out and it is just the motherboard, CPU, and PSU on a wood desk with nothing else connected and there is no response then the problems is probably a dead motherboard.

CPUs almost never randomly quit working. Either they have a problem ever since day 1 or they never have a problem.

The PSU and the motherboard are both much more likely to die than a CPU is.

If lights on the motherboard light up, the PSU is delivering something to the motherboard which should be good enough to get some kind of response even if it just turns on and right back off.

My guess is motherboard.
 

Not necessarily true. Ethernet ports and frequently USB are powered by the small, always on Aux 5 volt power supply inside the PSU. It also powers the startup circuits that detect when the case power switch is pressed. Except for input power, the Aux 5V PS is completely separate from the main power circuits in the PSU.

Even then "some kind of response" only tells you that you have a problem. It doesn't give you any clue about where that problem is.

Based on your configuration, I would suspect the power supply. Rosewills tend to be ... ummm ... excessively suboptimal.

Work systematically through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-posting-boot-problems
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.
The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboarding
If the system POST's here, you have a case shorting problem.

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:

Check for line power at the PSU input. Extension cords, power strips, and power cords do fail.

If you have power and no beeps, suspect components in likely order are PSU, motherboard, and CPU.
Try to replace the questionable PSU with a known good one. A brand new, untested, out of the box PSU is not a known good PSU.

Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The green wire will alway have 5 volts on it. When you press the power switch, the voltage should drop to 0 volts.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=youtube_gdata

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card. If you get this with motherboard graphics, your motherboard is bad.

Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card. In this case, you will POST successfully (single short beep). But your monitor will display a "missing signal" message.

In that case, the first thing you do is to test the monitor and data cable with another system to make sure it works. If the monitor works, the video card is bad. If you have motherboard graphics, again, the motherboard is bad.
 


The point was that "some kind of response" leads you down a whole different troubleshooting path than "no response of any kind".

If the led wasn't even on, I would have more reason to think bad PSU. Since it is on, I am more inclined to think bad motherboard.
 

the_deku_nutt

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Apr 21, 2012
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I submitted an RMA on my motherboard for a replacement/repair (hopefully replacement). In the meantime, I'll attempt all the suggestions given here. Thanks for the extensive and in depth responses from all. I'll repost once my problem has been repaired just let you know what it was.

Thanks again!
 

the_deku_nutt

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Apr 21, 2012
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I breadboarded my system down to its basic constituent components and bridged the power switch terminals as suggested. I received absolutely no beeps whatsoever, which conclusively determined the motherboard as the issue. Interestingly enough, I checked the particular motherboard on Newegg and the product had been discontinued. I suspect potentially weak design from the get-go. Thanks for all your time!