New Build, no power. How can I tell if my motherboard is dead?

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WannabeGeek_13

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Jun 8, 2012
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Building a new system. PSU is known as good because it worked fine in my old system a couple days ago.

  • ■ Mobo: Asrock AB350 Pro4
    ■ CPU: AMD Ryzen 7 1800X
    ■ RAM: Two 8GB sticks of T-force Dark. DDR4 3000
    ■ PSU: Seasonic 750 FX Gold

Symptoms:
Computer will not start, CPU fan & case fans never come on.

If I plug a USB drive into the MOBO, a little LED inside the thumbdrive lights up, so the Mobo is getting some sort of power.

I have tried starting it with 2 RAM sticks, 1 RAM stick and zero RAM sticks placed in various slots on the Mobo. No response to hitting the power button.

No luck when I took the mobo out of the case, either.

I've gone through all the checklists I can find.

I have tried shorting the power switch headers with a screwdriver

Unfortunately, I do not have a mobo speaker. I am looking for the CPU fan to start spinning to show that it's doing something.

Possible causes - how do I isolate / test next?

These are the possible causes I can think of. Maybe some of them are nonsensical, though, so I'm hoping to get more insight from you kind people.

■ Mobo was DOA
■RAM is not listed on the mobo support page in the list of compatible RAM. Would incompatible RAM cause this?
■When I first tried to start it up, I saw that the ATX power to the MOBO was loose, as was the RAM sticks. I wiggled one or the other and the CPU fan briefly (1/2 second?) came to life. Could I have killed the mobo when I did this?
■Would the CPU fan come on even with no RAM inserted? Seems that would be a good way to isolate the problem to the MOBO.
 
Solution
Satan-IR



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Satan-IR

Satan-IR

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Apr 18, 2014
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Have you tried clearing the CMOS?

Turn off, unplug from wall outlet, press and hold power button down for 15-20 seconds, then take the CMOS battery out, short clear CMOS jumpers (pins 2 and 3) for 10 seconds. See if this helps.

Yes the CPU fan should start spinning as soon as board receives power on signal. If the motherboard has a buzzer/speaker if you try to power up with NO RAM it should beep for lack of RAM based on the BIOS manufacturer's beep codes.

No CPU and case fan might indicate problem with PSU.

 
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WannabeGeek_13

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Jun 8, 2012
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I did not try clearing the CMOS, but I have now, and tried it with no RAM inserted. No change in the symptoms. PSU was working fine 2 days ago in another computer. I don't have a buzzer/speaker unfortunately. I do have a slick multimeter that I could hook up to the headers for the mobo speaker, but TBH I'm not sure what setting to put the multimeter. I do know that it can read PWM signals somehow.
 
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Satan-IR

Satan-IR

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OK then. If you have experience working with multimeters you can test the PSU output voltages. If it has a Low Pass and Frequency measurement capabilities you can measure duty cycles and PWM signals. I'm guessing you're not experienced with DMMs.

Not really safe to test PSU voltages while it's connected to a motherboard and it's powered on. I mean you can do it. Experienced people do that but you might just touch something and cause short circuits, if the boards in not dead that might just do it! You have to power it on by shorting the green wire/pin with any black wire/pin (ground) out of the case and disconnected from the motherboard and other peripherals.

There's a video tutorial here:

https://www.youtube.com/watch?v=ac7YMUcMjbw

I have to emphasize please DO NOT attempt this yourself if you've not worked with multimeters before and are not really sure what to do. You can electrocute yourself or damage the PSU and/or the multimeter.
 
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tsnor

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Also, before you get too far verify the simple stuff --> http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems Usually its something simple like the PSU has a power switch, and it's off. Everyone who builds PC gets caught by something simple sometime.

If that doesn't help, pull the MB from the case and place on cardboard. Connect just the PSU, CPU, CPU heatsink/fan to the MB. Run it. If the MB signals "no memory" via display or beep code then these three components appear to be working. Start adding back parts. If the MB does not signal "no memory" then one or more of those parts is bad. Replace PSU first if you have one you can swap in. RMA the MB first if you don't and your PSU is high quality like your Seasonic 750 FX Gold.
 
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